Study Guide: Midterm Exam
Concentrate your studies in the following areas. Questions for the Midterm Exam will come principally from this material.
Lutgens and Tarbuck Textbook:
Minerals (Chapter 1) * Know the definition of a mineral.
A mineral is a naturally occurring substance that is solid and inorganic representable by a chemical formula, usually abiogenic, and has an ordered atomic structure. It is different from a rock, which can be an aggregate of minerals or non-minerals and does not have a specific chemical composition. The exact definition of a mineral is under debate, especially with respect to the requirement a valid species be abiogenic, and to a lesser extent with regard to it having an ordered atomic structure. * Know the basic definition of a rock. * In geology, rock is a naturally occurring solid aggregate of one or more minerals or mineraloids. For example, the common rock granite is a combination of the quartz, feldspar and biotite minerals. The Earth's outer solid layer, the lithosphere, is made of rock. * Know how atoms of the same element are related. What do they have in common?
All atoms of the same element have the same number of protons in the nucleus and consequently have the same atomic number. All atoms of the same neutral element have the same number of electrons as well.
Atoms of an element usually have the same number of neutrons as protons. Atoms of the same element that have a different number of neutrons are called isotopes. Isotopes have the same atomic number but different atomic masses.
Atoms of an element share that element's chemical and physical properties, such as boiling point, melting point and stability.

* Know definitions for the following terms: valence electrons, nucleus, atom, element, ion, and chemical compound.
Valence electron: an electron in an outer shell of an atom that can be lost to or shared with another atom to form a molecule
Nucleus: the central and most important part of an object, movement, or group, forming the basis for its activity and growth
Atom: the basic unit of a chemical element
Element: each of more than one hundred substances that cannot be chemically interconverted or broken down into simpler substances and are primary constituents of matter. Each element is distinguished by its atomic number, i.e., the number of protons in the nuclei of its atoms.
Ion: an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
Chemical Compound: A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together in a defined spatial arrangement by chemical bonds. Chemical compounds can be molecular compounds held together by covalent bonds, salts held together by ionic bonds, intermetallic compounds held together by metallic bonds, or complexes held together by coordinate covalent bonds. Pure chemical elements are not considered chemical compounds, even if they consist of molecules that contain only multiple atoms of a single element, which are called diatomic molecules or polyatomic molecules.

* Know the difference between ionic and covalent bonds. Which is typically stronger?
In an ionic bond, the atoms are bound together by the attraction between oppositely-charged ions. For example, sodium and chloride form an ionic bond, to make NaCl, or table salt. In a covalent bond, the atoms are bound by shared electrons. If the electron is shared equally between the atoms forming a covalent bond, then the bond is said to be nonpolar. Usually, an electron is more attracted to one atom than to another, forming a polar covalent bond.
Covalent stronger * Know the components and structure of the silicon-oxygen tetrahedron that makes up silicate minerals.
It is a basic molecular building block of silicate minerals. It consists of 4 oxygen atoms arranged in a tetrahedron shape around a silicon atom. * Silicate Tetrahedron - Oxygen and silicon together form an exceedingly strong complex ion, the silicate anion (SiO4)4-. In the silicate anion, the oxygen ions pack into the smallest space possible for four large spheres. The smallest space is taken if the oxygens sit at the corners of a tetrahedron and the small silicon cation sits in the space between the oxygens at the center of the tetrahedron. Because the silicate anion has a negative charge (this means that each oxygen in the anion needs an electron to become stable) the oxygens must accept electrons from cations or share electrons with other silicate anions. Most silicate minerals contain a large number of silicate anions. * Know and understand the following physical properties of minerals: luster, color, streak, hardness, cleavage, fracture, and specific gravity.
Mineral luster: Luster is the property of minerals that indicates how much the surface of a mineral reflects light. The luster of a mineral is affected by the brilliance of the light used to observe the mineral surface. Luster of a mineral is described in the following terms:
Metallic The mineral is opaque and reflects light as a metal would.Submettalic The mineral is opaque and dull. The mineral is dark colored.Nonmettalic The mineral does not reflect light like a metal.
Nonmetallic minerals are described using modifiers that refer to commonly known qualities.

Mineral color: Most minerals have a distinctive color that can be used for identification. In opaque minerals, the color tends to be more consistent, so learning the colors associated with these minerals can be very helpful in identification. Translucent to transparent minerals have a much more varied degree of color due to the presence of trace minerals. Therefore, color alone is not reliable as a single identifying characteristic
Mineral streak: Streak is the color of the mineral in powdered form. Streak shows the true color of the mineral. In large solid form, trace minerals can change the color appearance of a mineral by reflecting the light in a certain way. Trace minerals have little influence on the reflection of the small powdery particles of the streak.
The streak of metallic minerals tends to appear dark because the small particles of the streak absorb the light hitting them. Non-metallic particles tend to reflect most of the light so they appear lighter in color or almost white.
Because streak is a more accurate illustration of the mineral’s color, streak is a more reliable property of minerals than color for identification.

Mineral hardness: Hardness is one of the better properties of minerals to use for identifying a mineral. Hardness is a measure of the mineral’s resistance to scratching. The Mohs scale is a set of 10 minerals whose hardness is known. The softest mineral, talc, has a Mohs scale rating of one. Diamond is the hardest mineral and has a rating of ten. Softer minerals can be scratched by harder minerals because the forces that hold the crystals together are weaker and can be broken by the harder mineral.
The following is a listing of the minerals of the Mohs scale and their rating: 1. Talc 2. Gypsum 3. Calcite 4. Fluorite 5. Apatite 6. Orthoclase Feldspar 7. Quartz 8. Topaz 9. Corundum 10. Diamond

Mineral cleavage: Cleavage is defined using two sets of criteria. The first set of criteria describes how easily the cleavage is obtained. Cleavage is considered perfect if it is easily obtained and the cleavage planes are easily distinguished. It is considered good if the cleavage is produced with some difficulty but has obvious cleavage planes. Finally it is considered imperfect if cleavage is obtained with difficulty and some of the planes are difficult to distinguish.
The second set of criteria is the direction of the cleavage surfaces. The names correspond to the shape formed by the cleavage surfaces: Cubic, rhombohedral, octahedral, dodecahedral, basal or prismatic. These criteria are defined specifically by the angles of the cleavage lines as indicated in the chart below:
Cleavage Type Angles
Cubic Cleaves in three directions @ 90o to one anotherRhombohedral Cleaves in three directions but not @ 90o to one anotherOctahedral Cleaves in four directionsDodecahedral Cleaves in six directionsBasal Cleaves in one directionPrismatic Cleaves in two directions
Fracture describes the quality of the cleavage surface. Most minerals display either uneven or grainy fracture, conchoidal (curved, shell-like lines) fracture, or hackly (rough, jagged) fracture.

Mineral fracture:
Mineral specific gravity: Specific Gravity of a mineral is a comparison or ratio of the weight of the mineral to the weight of an equal amount of water. The weight of the equal amount of water is found by finding the difference between the weight of the mineral in air and the weight of the mineral in water.

* What mineral found in nature is the hardest known to man? Name some of the softer minerals known.
Hardest: Diamond
Softest: Talc * What minerals are known for their perfect cleavage in one direction? What minerals are known for perfect cleavage in three directions?
Mica-one direction
Halite- three directions * Be able to define atomic number, atomic mass, protons, neutrons, and electrons. Also, know the following formula and be able to apply it: Atomic Mass = # of protons + # of neutrons.
Atomic number: the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.

Atomic mass: the mass of an atom of a chemical element expressed in atomic mass units. It is approximately equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes.

Proton: a stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign.

Neutron: a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen
Electron: a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids.

Atomic mass= #of protons + #of neutrons

* Know the eight most common elements in the earth’s crust. Also, know the different mineral groups (i.e., silicates, carbonates, sulfides, etc.). See Table 1.1 on page 39 for the non-silicate mineral groups. Which of the mineral groups is most common in the earth’s crust?
Oxygen 46.6%
Silicon 27.7
Aluminum 8.1
Iron 5.0
Calcium 3.6
Sodium 2.8
Potassium 2.6
Magnesium 2.1
Silicates, oxides, sulfates, sulfides, carbonates, native elements, and halides are all major mineral groups. * Non-silicate mineral group: A mineral that does not hold the silica tetrahedron is termed to be a non-silicate mineral. The second chief combination of minerals is those composed of chemical structures other than the silicon-oxygen tetrahedron. Non-silicate minerals are extremely different in their foundation and in its physical properties; and as such, are extremely significant for our understanding of a wide range of Earth processes. The majority basic group of non-silicate minerals is known as the native elements. Oxides * Sulfides * Sulfates * Halides * Carbonates
Rocks (Chapter 2)

* Be able to name and describe the three main rock types found in the earth’s crust (i.e., igneous, sedimentary, and metamorphic).
Igneous: Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may form with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. This magma can be derived from partial melts of pre-existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Over 700 types of igneous rocks have been described, most of them having formed beneath the surface of Earth's crust.
Sedimentary: are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle and accumulate or minerals to precipitate from a solution. Particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, sediment was formed by weathering and erosion in a source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers which are called agents of denudation. The sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust.[1] Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding. The study of sedimentary rocks and rock strata provides information about the subsurface that is useful for civil engineering, for example in the construction of roads, houses, tunnels, canals or other constructions. Sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores.
Metamorphic: arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form".[1] The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure (1500 bars),[2] causing profound physical and/or chemical change. The protolith may be sedimentary rock, igneous rock or another older metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and are classified by texture and by chemical and mineral assemblage (metamorphic facies). They may be formed simply by being deep beneath the Earth's surface, subjected to high temperatures and the great pressure of the rock layers above it. They can form from tectonic processes such as continental collisions, which cause horizontal pressure, friction and distortion. They are also formed when rock is heated up by the intrusion of hot molten rock called magma from the Earth's interior. The study of metamorphic rocks (now exposed at the Earth's surface following erosion and uplift) provides information about the temperatures and pressures that occur at great depths within the Earth's crust. Some examples of metamorphic rocks are gneiss, slate, marble, schist, and quartzite. * Have a basic understanding of the rock cycle.
Rock cycle: is a basic concept in geology that describes the dynamic transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. As the diagram to the right illustrates, each of the types of rocks is altered or destroyed when it is forced out of its equilibrium conditions. An igneous rock such as basalt may break down and dissolve when exposed to the atmosphere, or melt as it is subducted under a continent. Due to the driving forces of the rock cycle, plate tectonics and the water cycle, rocks do not remain in equilibrium and are forced to change as they encounter new environments. The rock cycle is an illustration that explains how the three rock types are related to each other, and how processes change from one type to another over time. * Know how crystal size in igneous rocks is related to cooling history.
Crystal size is determined by the amount of time the magma or lava has to cool. Lava, being erupted onto the surface cools quickly, resulting in small crystals. Magma which cools underground can take hundreds of thousands of years to cool, and therefore the mineral crystals grow larger.

* Know the basic differences between intrusive and extrusive igneous rocks. * One form of igneous rocks, intrusive rocks, derive directly from magma and solidifies within the earth. Since intrusive rocks are within the earth, they cool very slowly -- taking anywhere from thousands to millions of years to cool enough to completely solidify. The cooling rate of intrusive rocks enables the crystals to form that are visible to the naked eye, which gives them a coarse grain compared to extrusive rocks. This visible grain is called a phaneritic texture. Granite is one example of an intrusive igneous rock. * Extrusive rocks are formed from lava and form outside of the earth. When lava is exposed to the atmosphere or water outside of the earth, this causes the lava to cool very rapidly in comparison to intrusive rocks. This rapid cooling does not allow the rock time to form large crystals in the way that intrusive rocks do. Extrusive rocks have a fine-grained texture known to geologists as aphanitic, because the mineral crystals present within the rock are very small. Examples of extrusive igneous rocks are basalt and obsidian.

* Be able to describe the following igneous rock textures: fine-grained, vesicular, coarse-grained, glassy, and porphyritic.
Fine: mineral grains smaller than 1mm (need hand lens or microscope to see minerals)
Course: mineral grains easily visible (grains several mm in size or larger)
Vesicular: (Open spaces, bubbles)
Glassy: (NO CRYSTALS VISIBLE)
Porphyritic: (MIXED FINE AND COARSE)

* Know the basic differences between granitic (felsic) igneous rocks and basaltic (mafic) igneous rocks. Which is found in abundance is oceanic crust? Which is found in abundance in continental crust?
Granitic:
it is without a doubt the most common rock type on the continental land masses. Yosemite Valley in the Sierra Nevada and Mt. Rushmore are two notable examples of granitic rocks. But granitic "basement rock" can be found just about everywhere east of the Rockies if you're willing to dig through the dirt and sedimentary rocks at the surface. Granite is intrusive, which means that the magma was trapped deep in the crust, and probably took a very long time to cool down enough to crystallize into solid rock. This allows the minerals which form plenty of time to grow, and results in a coarse-textured rock in which individual mineral grains are easily visible.Granite is the ultimate silicate rock. As discussed elsewhere in greater detail, on average oxygen and silicon account for 75% of the earth's crust. The remaining 25% is split among several other elements, with aluminum and potassium contributing the most to the formation of the continental granitic rocks. Relatively small amounts of iron and magnesium occur, but since they have generally higher densities it's not surprising that there isn't very much in the granite. Due to the process of differentiation, most of the heavier elements are moving towards the core of the earth, allowing the silicon and oxygen to accumulate on the surface. And accumulate it has. Enough granitic "scum" has differentiated to the surface to cover 25% to 30% of the earth with the good stuff. We call this purified material felsic because of the relatively high percentage of silica and oxygen.
Basaltic: is extrusive. The magma from which it cools breaks through the crust of the earth and erupts on the surface. We call these types of events volcanic eruptions, and there are several main types. The volcanoes that make basalt are very common, and tend to form long and persistent zones of rifting in nearly all of the ocean basins. We now believe that these undersea volcanic areas represent huge spreading ridges where the earth's crust is separating. It's a lot like a cut on your arm, which will bleed until a scab forms. Basaltic magma is like the blood of the earth - it's what comes out when the earth's skin is cut the whole way through. As an eruption ends, the basalt "scab" heals the wound in the crust, and the earth adds some new seafloor crust. Because the magma comes out of the earth (and often into water) it cools very quickly, and the minerals have very little opportunity to grow. Basalt is commonly very fine grained, and it is nearly impossible to see individual minerals without magnification. Basalt is considered a mafic silicate rock. Among other characteristics, mafic minerals and rocks are generally dark in color and high in specific gravity. This is in large part due to the amount of iron, magnesium, and several other relatively heavy elements which "contaminate" the silica and oxygen. But this heavy stuff really isn't happy near the surface, and will take any opportunity it can to head for deeper levels. The trick is to heat the basalt back up again so it can melt and give the iron another shot at the core. It wants to be there, and heat is the key which unlocks the door.
As it turns out, most of the ocean floor is basalt, and most of the continents are granite. Basaltic crust is dark and thin and heavy, while granite is light and accumulates into continent-sized rafts which bob about like corks in this "sea of basalt." When a continent runs into a piece of seafloor, it's much like a Mac truck running into a Volkswagon. Not very pretty, but at least there's a clear winner. And the seafloor basalt ends up in pretty much the same position as does the VW - under the truck (or continent, as the case may be). This may seem like a drag for the basalt, but remember that it isn't all that happy on the surface anyway, and this gives it the heat it needs to re-melt and try to complete the differentiation process which was so rudely interrupted at the spreading ridge. If successful and allowed to continue, what's left behind is a "purified" magma with most of the iron, magnesium, and other heavy elements removed. When it cools, guess what forms? And the continental land mass just got a wee bit larger. Know which igneous rock is popular as a building material. Granite * Know the differences between mechanical and chemical weathering. Be able to define and discuss each. * Differences: During chemical weathering, the substance of the rock physically changes. Certain elements or compounds, such as water or oxygen, can cause chemical reactions in a rock, making it softer or dissolving the rocks altogether. In contrast, mechanical weathering causes a breakdown of rocks without a change in chemical composition. Also known as physical weathering, this type of weathering is commonly caused by the movement of the Earth or the freezing and thawing of water. * Examples of Chemical: Chemical weathering occurs when chemical reactions take place inside a rock's structure, altering the composition of the rock itself. Acid rain is one cause of such weathering. Gases such as carbon dioxide and oxygen can cause chemical weathering. Oxidation occurs when oxygen attaches to certain substances in the rock, changing the composition of the rock. Carbonation is a similar process that occurs with carbon dioxide, in which rocks actually dissolve in rain water. Plants can also cause chemical weathering. Mosses and other plants growing on and around a rock can release acids that can cause chemical weathering.
Water is another factor that can cause chemical weathering. Hydration is one form of water weathering. During hydration, a water molecule will attach to other molecules in a substance, such as clay, causing it to swell. Hydrolysis is another form of water weathering. In hydrolysis, water molecules moving through the rock may attach to certain elements, physically changing the makeup of the rock's structure, making it softer and more susceptible to mechanical weathering.

Examples of Mechanical: * Water is also responsible for mechanical weathering. When water freezes, it expands. If the water is inside a rock, that expansion can cause cracks or even cause bits of the rock to fall off completely. Temperature can cause a similar problem. As temperatures grow warmer, the rocks themselves expand.
Movement of the Earth can also cause mechanical weathering. The crust of the Earth is in constant motion. The same rubbing and collision of rocks that can lead to earthquakes can also cause weathering in rocks.

* Know the different physical processes that mechanically weather rock material (e.g., frost wedging, sheeting, biological activity). Likewise, be able to identify the processes that chemically weather rock material (e.g., oxidation, decomposition [in the presence of acid], hydrolysis [in the presence of water]).

Mechanical processes that weather rock: Ice. The formation of ice in the myriad of tiny cracks and joints in a rock's surface slowly pries it apart over thousands of years. Frost wedging results when the formation of ice widens and deepens the cracks, breaking off pieces and slabs. Frost wedging is most effective in those climates that have many cycles of freezing and thawing. Frost heaving is the process by which rocks are lifted vertically from soil by the formation of ice. Water freezes first under rock fragments and boulders in the soil; the repeated freezing and thawing of ice gradually pushes the rocks to the surface. Exfoliation. If a large intrusion is brought to the surface through tectonic uplift and the erosion of overlying rocks, the confining pressure above the intrusion has been released, but the pressure underneath is still being exerted, forcing the rock to expand. This process is called unloading. Because the outer layers expand the most, cracks, or sheet joints, develop that parallel the curved outer surface of the rock. Sheet joints become surfaces along which curved pieces of rock break loose, exposing a new surface. This process is called exfoliation; large rounded landforms (usually intrusive rocks) that result from this process are called exfoliation domes. Examples of exfoliation domes are Stone Mountain, Georgia, and Half Dome in Yosemite National Park.
Friction and impact. Rocks are also broken up by friction and repeated impact with other rock fragments during transportation. For example, a rock fragment carried along in a river's current continuously bounces against other fragments and the river bottom and eventually is broken into smaller pieces. This process occurs also during transportation by wind and glacial ice.
Other processes. Less important agents of mechanical weathering include the burrowing of animals, plant roots that grow in surface cracks, and the digestion of certain minerals, such as metal sulfides, by bacteria. Daily temperature changes, especially in those regions where temperatures can vary by 30 degrees centigrade, result in the expansion and contraction of minerals, which weaken rocks. Extreme temperature changes, such as those produced by forest fires, can force rocks to shatter.
Chemical process that weather rock: Water. Chemical weathering is most intense in areas that have abundant water. Different minerals weather at different rates that are climate dependent. Ferromagnesian minerals break down quickly, whereas quartz is very resistant to weathering. In tropical climates, where rocks are intensely weathered to form soils, quartz grains are typically the only component of the rock that remains unchanged. Alternatively, in dry desert climates, minerals normally susceptible to weathering in wet environments (such as calcite) can be much more resistant.
Acids. Acids are chemical compounds that decompose in water to release hydrogen atoms. Hydrogen atoms frequently substitute for other elements in mineral structures, breaking them down to form new minerals that contain the hydrogen atoms. The most abundant natural acid is carbonic acid, a weak acid that consists of dissolved carbon dioxide in water. Rainwater usually contains some dissolved carbon dioxide and is slightly acidic. The burning of coal, oil, and gasoline releases carbon dioxide, nitrogen, and sulfur into the atmosphere, which react with rainwater to form much stronger carbonic, nitric, and sulfuric acids that damage the environment (acid rain).
Other acids that can affect the formation of minerals in the nearsurface weathering environment are organic acids derived from plant and humus material. Strong acids that are naturally occurring in the environment are rare—they include the sulfuric acids and hydrofluoric acids released during volcanic and hot spring activity.
Solution weathering is the process by which certain minerals are dissolved by acidic solutions. For example, calcite in limestone is dissolved easily by carbonic acid. Rain that percolates through cracks and fissures in limestone beds dissolves calcite, making wider cracks that can ultimately develop into cave systems.
Oxygen. Oxygen is present in air and water and is an important part of many chemical reactions. One of the more common and visible chemical weathering reactions is the combination of iron and oxygen to form iron oxide (rust). Oxygen reacts with iron‐bearing minerals to form the mineral hematite (Fe2O3) , which weathers a rusty brown. If water is included in the reaction, the resultant mineral is called Iimonite (Fe2O3· nH2O) , which is yellow‐brown. These minerals often stain rock surfaces a reddish‐brown to yellowish color. * Know the differences between detrital and chemical sedimentary rocks. * Detrital rocks are sometimes referred to as clastic sedimentary rocks because they are made up of clasts or rock fragments. * The word 'detrital' actually means 'rubbing away,' and we see that detrital rocks form when pre-existing rocks are rubbed away or weathered by forces such as water, ice and wind, leaving behind smaller rock fragments. * So you can say that detrital sedimentary rocks are composed of rock fragments that have been weathered from pre-existing rocks. Because these rocks are created by the breakdown of other rocks, they are the most common rocks we see on the surface of the earth. * As these pieces of rocks get chipped away, they get carried by nature and roll and tumble and break up even more until they find a resting place in a low-lying area, like a valley or the basin of a lake or ocean where the grains of sediment accumulate and get cemented together, forming layers or strata. * Chemical sedimentary rocks are a different type of sedimentary rock because they are not made up of weathered sediment grains; instead they are composed of mineral crystals that form out of solution. In other words, chemical sedimentary rocks contain crystals and other elements that have been dissolved out of water. One way this can happen is if a body of water becomes so saturated with minerals that the minerals no longer fit and there are too many for all of them to remain dissolved. The result is that some of the minerals precipitate, meaning the solid mineral crystals separate out of the solution. * This is similar to what happens when moisture builds up in a cloud to the point where the cloud is so saturated that it can no longer hold the water and the water is released as rain. We see some types of limestone formed in this way when the abundant mineral calcite precipitates out of solution

* What physical property is used principally to classify detrital sedimentary rocks? * Detrital sedimentary rocks are mainly classified by the size of their grains. The grains are different size because of the amount of weathering they were exposed to. For example, if you have a fragment of rock located near the pre-existing rock it broke away from, it might be fairly large, say, the size of a basketball or larger. This would be considered a boulder. * If that boulder got carried away from the rock it originated from by forces like water, for instance, then it might get broken down even more to the size of a softball. At this point it would be called a cobble, like you might see in a cobblestone street of an old-time village. * The pieces could continue to weather and leave us with a grape-sized grain, or pebble, followed by grains of sand, like you would find on the beach, and then silt, which is very fine sand, and finally clay, which is the finest of them all and looks and feels like flour. * These grains of sediments are what get cemented together to form sedimentary rocks. So if you have clay-sized grains cemented together, you will get shale. If you ever want to impress someone by telling them that you can break rocks with your bare hands, then I suggest grabbing a piece of shale, because it deposits in fragile layers that are easily broken. * If you have silt-sized grains cemented together, you have siltstone, which is somewhat like a gritty form of shale but without the layers. * If you have sand-sized grains cemented together, you have sandstone. * Sandstone is a porous and permeable rock, which allows water to easily move through it. Because of this, sandstone makes a great aquifer for the underground storage of water. * If you have rock that contains grains larger than sand, you have conglomerate if it contains large rounded grains, and you have breccia, meaning 'broken,' if the rock contains angular grains. Rounded grains would be the result of sediments that were carried and smoothed by water, and angular or broken fragments could result from an event such as a rockslide down the side of a mountain.

* Name some common minerals found together in detrital sedimentary rocks.
The most common minerals in detrital sedimentary rocks are quartz grains and clay. * Name the most abundant chemical sedimentary rock found on earth.
Limestone
* What are evaporite deposits? Where do these typically form? Evaporites are layered crystalline sedimentary rocks that form from brines generated in areas where the amount of water lost by evaporation exceeds the total amount of water from rainfall and influx via rivers and streams. The mineralogy of evaporite rocks is complex, with almost 100 varieties possible, but less than a dozen species are volumetrically important. Minerals in evaporite rocks include carbonates (especially calcite, dolomite, magnesite, and aragonite), sulfates (anhydrite and gypsum), and chlorides (particularly halite, sylvite, and carnallite), as well as various borates, silicates, nitrates, and sulfocarbonates. Evaporite deposits occur in both marine and nonmarine sedimentary successions. * Though restricted in area, modern evaporites contribute to genetic models for explaining ancient evaporite deposits. Modern evaporites are limited to arid regions (those of high temperature and low rates of precipitation), for example, on the floors of semidry ephemeral playa lakes in the Great Basin of Nevada and California, across the coastal salt flats (sabkhas) of the Middle East, and in salt pans, estuaries, and lagoons around the Gulf of Suez. Ancient evaporates occur widely in the Phanerozoic geologic record, particularly in those of Cambrian (from 570 to 505 million years ago), Permian (from 286 to 245 million years ago), and Triassic (from 245 to 208 million years ago) age, but are rare in sedimentary sequences of Precambrian age. They tend to be closely associated with shallow marine shelf carbonates and fine (typically rich in iron oxide) mudrocks. Because evaporite sedimentation requires a specific climate and basin setting, their presence in time and space clearly constrains inferences of paleoclimatology and paleogeography. Evaporite beds tend to concentrate and facilitate major thrust fault horizons, so their presence is of particular interest to structural geologists. Evaporites also have economic significance as a source of salts and fertilizer. * All evaporite deposits result from the precipitation of brines generated by evaporation. Laboratory experiments can accurately trace the evolution of brines as various evaporite minerals crystallize. Normal seawater has a salinity of 3.5 percent (or 35,000 parts per million), with the most important dissolved constituents being sodium and chlorine. When seawater volume is reduced to one-fifth of the original, evaporite precipitation commences in an orderly fashion, with the more insoluble components (gypsum and anhydrite) forming first. When the solution reaches one-tenth the volume of the original, more soluble minerals like sylvite and halite form. Natural evaporite sequences show vertical changes in mineralogy that crudely correspond to the orderly appearance of mineralogy as a function of solubility but are less systematic. * Typically, evaporite deposits occur in closed marine basins where evaporation exceeds inflow. The deposits often show a repeated sequence of minerals, indicating cyclic conditions with a mineralogy determined by solubility. The most important minerals and the sequence in which they form include calcite, gypsum, anhydrite, halite, polyhalite, and lastly potassium and magnesium salts such as sylvite, carnallite, kainite, and kieserite; anhydrite and halite dominate. These sequences have been reproduced in laboratory experiments and, therefore, the physical and chemical conditions for evaporite formation are well known. * In contrast to basin deposits, extensive thin-shelf deposits are known and are thought to be the result of shallow, ephemeral seas. Non-marine evaporites formed by streams flowing into closed depressions, especially in arid regions, give rise to deposits of borates, nitrates, and sodium carbonates. Such deposits occur in Utah and southern California in the United States.

* In terms of sedimentary rocks, define these terms: lithification, cementation, strata, and fossils.
Lithification: the process in which sediments compact under pressure, expel connate fluids, and gradually become solid rock. Essentially, lithification is a process of porosity destruction through compaction and cementation. Lithification includes all the processes which convert unconsolidated sediments into sedimentary rocks. Petrification, though often used as a synonym, is more specifically used to describe the replacement of organic material by silica in the formation of fossils
Cementation: involves ions carried in groundwater chemically precipitating to form new crystalline material between sedimentary grains. The new pore-filling minerals form "bridges" between original sediment grains, thereby binding them together. In this way sand becomes "sandstone", and gravel becomes "conglomerate" or "breccia". Cementation occurs as part of the diagenesis or lithification of sediments. Cementation occurs primarily below the water table regardless of sedimentary grain sizes present. Large volumes of pore water must pass through sediment pores for new mineral cements to crystallize and so millions of years are generally required to complete the cementation process. Common mineral cements include calcite, quartz or silica phases like cristobalite, iron oxides, and clay minerals, but other mineral cements also occur.
Strata: Geology A bed or layer of sedimentary rock having approximately the same composition throughout
Fossils: are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. * What is metamorphism? a change in the constitution of rock; specifically : a pronounced change effected by pressure, heat, and water that results in a more compact and more highly crystalline condition

* Name and describe the two basic types of metamorphism (i.e., contact and regional).
Metamorphism is the change of rocks. Contact metamorphism occurs in a small space, around an area where lava has seeped up nearer to the surface of the earth. The heat of the lava changes the rocks. Regional metamorphism occurs in large areas. They are changed by the pressure exerted from moving tectonic plates. * Be able to identify the agents of metamorphism. * HEAT contributes to the process in two ways. First, atoms may combine differently at different temperatures. This means that a mineral stable at one temperature might become unstable at a higher (or lower) temperature and be converted to a different mineral with a more stable atomic structure. This may or may not involve changing the exact elemental composition. Second, heat makes practically all chemical reactions go faster, meaning that mineral transformations are much easier at higher temperature. * 2. PRESSURE also has two effects. As with heat, it can control which minerals or forms of minerals are stable. Some minerals may be converted to minerals with similar composition but different atomic packing simply because pressure is increased. The exact nature of the pressure is not important in this case, only the amount. Thus the CONFINING (or LITHOSTATIC) PRESSURE created by deep burial of rocks under sediment may have this effect as well as the DIRECTED (or DIFFERENTIAL) PRESSURE produced by converging plates. The second effect of pressure is to reorient minerals with linear or platy structure or to create a preferred orientation of them as they form. Thus elongate minerals such as amphiboles, or platy minerals such as clays or micas tend to align themselves parallel to each other when under pressure. This only happens when there is directed pressure; confining pressure does not accomplish it. The diagram illustrates the effect. A texture of this sort in a metamorphic rock is called FOLIATION and the rocks are said to be FOLIATED.
FLUIDS serve only to speed up other metamorphic processes, or perhaps even allow them to happen at all. Chemical reactions require water, and most proceed much faster as the amount of water goes up. Dissolved ions in the fluid also make those mineral transformations that require chemical changes in the minerals to occur, whether by supplying needed ions or flushing away excess ones.

* What is foliation in metamorphic rocks? Foliated metamorphic rocks have a parallel and flat mineral arrangement, giving the rock a flaky or banded appearance. This texture forms in all types of metamorphic environments, but the resulting rock is determined by how intense the heat and pressure is. The heat and pressure can cause several different things to happen to the mineral grains within the parent rock including rotation of the mineral grains into alignment or recrystallization of minerals in a preferred direction. Compressional stress can actually squash rounded mineral grains into an oblong shape, which are also aligned in a preferred direction.

* Know the differences between foliated and non-foliated metamorphic textures. Be able to give examples of each (i.e., gneiss is foliated; quartzite is non-foliated; etc.). * Foliated Texture * A foliated metamorphic rock will have banded minerals. The mineral flakes will appear to be parallel to the rock and will look layered. When a foliated rock breaks, a thin rock fragment will result.
Nonfoliated Texture * A nonfoliated rock will have almost the opposite texture. The minerals will appear to be randomly oriented without obvious banding and have a granular appearance. Unlike a foliated rock, there will be no layers and they will not flake apart into thin layers when broken.
Foliated Compostion * Slate
Foliated rocks are most often formed from mudstones and contain "fine-grained" or "platy" minerals that are usually too small to see with the naked eye; although some can be seen without aid. Examples of foliated rocks are slate, phyllite and schist.
Nonfoliated Composition * Marble
Nonfoliated rocks contain more coarse grained minerals and generally have a random shape. Because of this, these rocks are very granular in appearance. Examples of nonfoliated rocks are quartzite, marble and anthracite coal.

Landscapes Fashioned by Water (Chapter 3)

What is mass wasting? What force is primarily responsible for mass wasting? the geomorphic process by which soil, sand, regolith, and rock move downslope typically as a mass, largely under the force of gravity, but frequently affected by water and water content as in submarine environments and mudslides.[1] Types of mass wasting include creep, slides, flows, topples, and falls, each with its own characteristic features, and taking place over timescales from seconds to years. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth, Mars, Venus, and Jupiter's moon Io.
When the gravitational force acting on a slope exceeds its resisting force, slope failure (mass wasting) occurs. The slope material's strength and cohesion and the amount of internal friction between material help maintain the slope's stability and are known collectively as the slope's shear strength. The steepest angle that a cohesionless slope can maintain without losing its stability is known as its angle of repose. When a slope possesses this angle, its shear strength perfectly counterbalances the force of gravity acting upon it.
Mass wasting may occur at a very slow rate, particularly in areas that are very dry or those areas that receive sufficient rainfall such that vegetation has stabilized the surface. It may also occur at very high speed, such as in rock slides or landslides, with disastrous consequences, both immediate and delayed, e.g., resulting from the formation of landslide dams.
Factors that change the potential of mass wasting include: change in slope angle, weakening of material by weathering, increased water content; changes in vegetation cover, and overloading.

* Have a basic understanding of the hydrologic cycle. is a conceptual model that describes the storage and movement of water between the biosphere, atmosphere, lithosphere, and the hydrosphere (see Figure 1). Water on our planet can be stored in any one of the following major reservoirs: atmosphere, oceans, lakes, rivers, soils, glaciers, snowfields, and groundwater. Water moves from one reservoir to another by way of processes like evaporation, condensation, precipitation, deposition, runoff, infiltration, sublimation, transpiration, melting, and groundwater flow. The oceans supply most of the evaporated water found in the atmosphere. Of this evaporated water, only 91% of it is returned to the ocean basins by way of precipitation. The remaining 9% is transported to areas over landmasses where climatological factors induce the formation of precipitation. The resulting imbalance between rates of evaporation and precipitation over land and ocean is corrected by runoff and groundwater flow to the oceans. * Know the various “loads” in a river (i.e., dissolved load, suspended load, and bed load). What size particles are typically carried in each type of load?
Dissolved load: Dissolved load is the term for material, especially ions from chemical weathering, that are carried in solution by a stream. The dissolved load contributes to the total amount of material removed from a catchment. The amount of material carried as dissolved load is typically much smaller than the suspended load, though this is not always the case. Dissolved load comprises a significant portion of the total material flux out of a landscape, and its composition is important in regulating the chemistry and biology of the stream.
Suspended load: is the portion of the sediment that is carried by a fluid flow which settle slowly enough such that it almost never touches the bed. It is maintained in suspension by the turbulence in the flowing water and consists of particles generally of the fine sand, silt and clay size.
Bed load: describes particles in a flowing fluid (usually water) that are transported along the bed. Bed load is complementary to suspended load and wash load.Bed load moves by rolling, sliding, and/or saltating (hopping).Generally, bed load downstream will be smaller and more rounded than bed load upstream (a process known as downstream fining). This is due in part to attrition and abrasion which results from the stones colliding with each other and against the river channel, thus removing the rough texture (rounding) and reducing the size of the particles. However, selective transport of sediments also plays a role in relation to downstream fining: smaller-than average particles are more easily entrained than larger-than average particles, since the shear stress required to entrain a grain is linearly proportional to the diameter of the grain. However, the degree of size selectivity is restricted by the hiding effect described by Parker and Klingeman (1982), wherein larger particles protrude from the bed whereas small particles are shielded and hidden by larger particles, with the result that nearly all grain sizes become entrained at nearly the same shear stress.

* Be able to define these terms: stream discharge, stream gradient, longitudinal profile.
Stream discharge: volume rate of water flow, including any suspended solids (e.g. sediment), dissolved chemicals (e.g. CaCO3(aq)), and/or biologic material (e.g. diatoms), which is transported through a given cross-sectional area.[1] Frequently, other terms synonymous with discharge are used to describe the volumetric flow rate of water and are typically discipline dependent. For example, a fluvial hydrologist studying natural river systems may define discharge as streamflow, whereas an engineer operating a reservoir system might define discharge as outflow, which is contrasted with inflow.
Stream gradient: A high gradient indicates a steep slope and rapid flow of water (i.e. more ability to erode); whereas a low gradient indicates a more nearly level stream bed and sluggishly moving water, that may be able to carry only small amounts of very fine sediment. High gradient streams tend to have steep, narrow V-shaped valleys, and are referred to as young streams. Low gradient streams have wider and less rugged valleys, with a tendency for the stream to meander.
Longitudinal profile: A cross section of a stream or valley beginning at the source and continuing to the mouth. These profiles are drawn to illustrate the gradient of the stream.

* Be able to determine stream gradient using the following formula: (change in elevation [in meters]) divided by (change in horizontal distance of flow [in kilometers]). For example, if a stream decreases in elevation 100 meters over a flow distance of 500 kilometers, then the stream gradient is 100 meters/500 kilometers = 0.2 m/km.

* Know the difference between stream capacity and stream competence.
Stream capacity: The ability of a stream to carry detritus, measured at a given point per unit of time.
Stream competence: Stream competence reflects the ability of a stream to transport a particular size of particle (e.g., boulder, pebble, etc). With regard to calculation of stream capacity and competence, streams broadly include all channelized movement of water, including large movements of water in rivers.
Under normal circumstances, the major factor affecting stream capacity and stream competence is channel slope. Channel slope (also termed stream gradient) is measured as the difference in stream elevation divided by the linear distance between the two measuring points. The velocity of the flow of water is directly affected by channel slope, the greater the slope the greater the flow velocity. In turn, an increased velocity of water flow increases stream competence. The near level delta at the lower end of the Mississippi River is a result of low stream velocities and competence. In contrast, the Colorado River that courses down through the Grand Canyon (where the river drops approximately 10 ft per mile [3 m/1.6 km]) has a high stream velocity that results in a high stream capacity and competence.
Channelization of water is another critical component affecting stream capacity and stream competence. If a stream narrows, the velocity increases. An overflow or broadening of a stream channel results in decreased stream velocities, capacity, and competence.
The amount of material (other than water) transported by a stream is described as the stream load. Stream load is directly proportional to stream velocity and stream gradient and relates the amount of material transported past a point during a specified time interval. The greater the velocity, the greater the sum of the mass that can be transported by a stream (stream load). Components of stream load contributing to stream mass include the suspended load, dissolved load, and bed load. Broad, slow moving streams are highly depositional (low stream capacity) while high velocity streams have are capable of moving large rocks (high stream competence).

Define base level. What is the ultimate base level? Sea level the lowest level to which moving water can erode a land surface such as the bed of a stream, lake, or sea

* In terms of stream erosion, what is the difference between a V-shaped valley (eroding well above base level) and wide river valleys with meandering rivers (eroding very close to base level)?
A V-shaped valley, sometimes called a river valley, is a narrow valley with steeply sloped sides that appear similar to the letter "V" from a cross-section. They are formed by strong streams, which over time have cut down into the rock through a process called downcutting. These valleys form in mountainous and/or highland areas with streams in their "youthful" stage. At this stage, streams flow rapidly down steep slopes.
An example of a V-shaped valley is the Grand Canyon in the Southwestern United States. After millions of years of erosion, the Colorado River cut throughrock of the Colorado Plateau and formed a steep sided canyon V-shaped canyon known today as the Grand Canyon.

U-Shaped Valley
A U-shaped valley is a valley with a profile similar to the letter "U." They are characterized by steep sides that curve in at the base of the valley wall. They also have broad, flat valley floors. U-shaped valleys are formed by glacial erosion as massive mountain glaciers moved slowly down mountain slopes during the last glacation. U shaped valleys are found in areas with high elevation and in high latitudes, where the most glaciation has occurred. Large glaciers that have formed in high latitudes are called continental glaciers or ice sheets, while those forming in mountain ranges are called alpine or mountain glaciers.
Due to their large size and weight, glaciers are able to completely alter topography, but it is the alpine glaciersthat formed most of the world's U-shaped valleys. This is because they flowed down pre-existing river or V-shaped valleys during the last glaciation and caused the bottom of the "V" to level out into a "U" shape as the ice eroded the valley walls, resulting in a wider, deeper valley. For this reason, U-shaped valleys are sometimes referred to as glacial troughs.

One of the world's most famous U-shaped valleys is Yosemite Valley in California. It has a broad plain that now consists of the Merced River along with granite walls that were eroded by glaciers during the last glaciation

* Be able to define the following terms: floodplain, cutoff, oxbow lake, cut bank, and point bar.
Floodplain: an area of land adjacent to a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge.[1] It includes the floodway, which consists of the stream channel and adjacent areas that actively carry flood flows downstream, and the flood fringe, which are areas inundated by the flood, but which do not experience a strong current. In other words, a floodplain is an area near a river or a stream which floods when the water level reaches flood stage.

Cutoff:

Oxbow lake: a U-shaped body of water that forms when a wide meander from the main stem of a river is cut off, creating a free-standing body of water. This landform is so named for its distinctive curved shape, resembling the bow pin of an oxbow. In Australia, an oxbow lake is known as a billabong, from the indigenous language Wiradjuri. In south Texas, oxbows left by the Rio Grande River are called resacas.

The word "oxbow" can also refer to a U-shaped bend in a river or stream, whether or not it is cut off from the main stream.[
Cut bank: the outside bank of a water channel (stream), which is continually undergoing erosion.[1] Cut banks are found in abundance along mature or meandering streams, they are located on the outside of a stream bend, known as a meander, opposite the slip-off slope on the inside of the bend. They are shaped much like a small cliff, and are formed by the erosion of soil as the stream collides with the river bank. As opposed to a point bar which is an area of deposition, a cut bank is an area of erosion.

Typically, cut banks are nearly vertical and often expose the roots of nearby plant life. Often, particularly during periods of high rainfall and higher-than average water levels, trees and poorly placed buildings can fall into the stream due to mass wasting events. Given enough time, the combination of erosion along cut banks and deposition along point bars can lead to the formation of an oxbow lake.
Point bar: a depositional feature made of alluvium that accumulates on the inside bend of streams and rivers below the slip-off slope. Point bars are found in abundance in mature or meandering streams. They are crescent-shaped and located on the inside of a stream bend, being very similar to, though often smaller than, towheads, or river islands.

Point bars are composed of sediment that is well sorted and typically reflects the overall capacity of the stream. They also have a very gentle slope and an elevation very close to water level. Since they are low-lying, they are often overtaken by floods and can accumulate driftwood and other debris during times of high water levels. Due to their near flat topography and the fact that the water speed is slow in the shallows of the point bar they are popular rest stops for boaters and rafters. However, camping on a point bar can be dangerous as a flash flood that raises the stream level by as little as a few inches (centimetres) can overwhelm a campsite in moments.

A point bar is an area of deposition whereas a cut bank is an area of erosion.

Point bars are formed as the secondary flow of the stream sweeps and rolls sand, gravel and small stones laterally across the floor of the stream and up the shallow sloping floor of the point bar.

* Know and be able to describe the four basic stream drainage patterns (i.e., dendritic, radial, rectangular, and trellis). In what types of geologic conditions do each tend to form? Which is the most common?
Dendritic: In a dendritic system, there are many contributing streams (analogous to the twigs of a tree), which are then joined together into the tributaries of the main river (the branches and the trunk of the tree, respectively). They develop where the river channel follows the slope of the terrain. Dendritic systems form in V-shaped valleys; as a result, the rock types must be impervious and non-porous

Radial: In a radial drainage system, the streams radiate outwards from a central high point. Volcanoes usually display excellent radial drainage. Other geological features on which radial drainage commonly develops are domes and laccoliths. On these features the drainage may exhibit a combination of radial patterns.[2]

Rectangular: Rectangular drainage develops on rocks that are of approximately uniform resistance to erosion, but which have two directions of jointing at approximately right angles. The joints are usually less resistant to erosion than the bulk rock so erosion tends to preferentially open the joints and streams eventually develop along the joints. The result is a stream system in which streams consist mainly of straight line segments with right angle bends and tributaries join larger streams at right angles.[2]

Trellis: The geometry of a trellis drainage system is similar to that of a common garden trellis used to grow vines. As the river flows along a strike valley, smaller tributaries feed into it from the steep slopes on the sides of mountains. These tributaries enter the main river at approximately 90 degree angles, causing a trellis-like appearance of the drainage system. Trellis drainage is characteristic of folded mountains, such as the Appalachian Mountains in North America

* Know the difference between an aquifer and an aquitard.
An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer,[1] and aquiclude (or aquifuge), which is a solid, impermeable area underlying or overlying an aquifer. If the impermeable area overlies the aquifer pressure could cause it to become a confined aquifer

* Know the different zones of groundwater (i.e., zone of saturation, unsaturated zone, belt of soil moisture). Be able to describe each (generally)
Zone of saturation: an area of soil or rock below the level of the water table where all the voids are filled with water
Unsaturated zone: The unsaturated zone is that portion of the subsurface in which the intergranular openings of the geologic medium contain both water and air. The unsaturated zone, also known as the vadose zone or the zone of aeration, extends downward from the land surface to the top of the underlying saturated zone . Water in the pores of this zone is at a pressure that is lower than atmospheric pressure . Most of the water that eventually recharges the saturated zone must first pass through the unsaturated zone
Belt of soil moisture: Belt from which water may be used by plants or withdrawn by soil evaporation. Some of the water passes down into the intermediate belt, where it may be held by molecular attraction against the influence of gravity.

* What is the water table? the level below which the ground is saturated with water

* Know the difference between porosity and permeability in soil/rock.

Porosity is a measure of how much of a rock is open space. This space can be between grains or within cracks or cavities of the rock. Permeability is a measure of the ease with which a fluid (water in this case) can move through a porous rock. * Understand and be able to define the following: hot springs, geysers, cone of depression, and land subsidence. In most cases, from where does the heat come to “power” hot springs and geysers?
Hot springs: a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are geothermal hot springs in many locations all over the crust of the earth.

Geysers: a hot spring in which water intermittently boils, sending a tall column of water and steam into the air.
Cone of depression: occurs in an aquifer when groundwater is pumped from a well. In an unconfined aquifer (water table), this is an actual depression of the water levels. In confined aquifers (artesian), the cone of depression is a reduction in the pressure head surrounding the pumped well.
When a well is pumped, the water level in the well is lowered. By lowering this water level, a gradient occurs between the water in the surrounding aquifer and the water in the well. Because water flows from high to low water levels or pressure, this gradient produces a flow from the surrounding aquifer into the well.
As the water flows into the well, the water levels or pressure in the aquifer around the well decrease. The amount of this decline becomes less with distance from the well, resulting in a cone-shaped depression radiating away from the well. This, in appearance, is similar to the effect one sees when the plug is pulled from a bathtub.
Land subsidence: the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation. Ground subsidence is of concern to geologists, geotechnical engineers and surveyors.

* What is an artesian well? Under what geologic conditions are these wells found? a well drilled through impermeable rocks into strata where water is under enough pressure to force it to the surface without pumping
Inclined aquafier sandwiched between impervious rock layers above and below are conditions necessary to form

* Karst topography describes topography that evidences the erosional effects of groundwater. What are some topographic evidences of karst topography? landscape formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterised by underground drainage systems with sinkholes, dolines, and caves.[1] It has also been documented for weathering-resistant rocks, such as quartzite, given the right conditions.[2] Subterranean drainage may limit surface water with few to no rivers or lakes. However, in regions where the dissolved bedrock is covered (perhaps by debris) or confined by one or more superimposed non-soluble rock strata, distinctive karst surface developments might be totally missing. * Know the difference between stalactites and stalagmites. Where do they form (i.e., in the zone of saturation or the unsaturated zone)? a type of formation that hangs from the ceiling of caves, hot springs, or manmade structures such as bridges and mines. Any material which is soluble, can be deposited as a colloid, or is in suspension, or is capable of being melted, may form a stalactite. Stalactites may be composed of amberat, lava, minerals, mud, peat, pitch, sand, and sinter.[1][2] A stalactite is not necessarily a speleothem, though speleothems are the most common form of stalactite because of the abundance of limestone caves.[1][3]
The corresponding formation on the floor of the cave is known as a stalagmite. is a type of rock formation that rises from the floor of a cave due to the accumulation of material deposited on the floor from ceiling drippings. Stalagmites may be composed of amberat, lava, minerals, mud, peat, pitch, sand, and sinter.[2][3]
The corresponding formation hanging down from the ceiling of a cave is a stalactite.

* How do sinkholes form? when limestone bedrock dissolves and leaves a large cavity. The ground above then caves in, taking homes, trees and other objects on top with it.
Glaciers (Chapter 4) * Know how much of the earth’s land area was covered by glaciers during the last ice age. How much of the earth’s surface is covered by glaciers today?
Thirty percent of the earth's surface was covered in ice at the peak of the ice age, but now there is only ten percent of the earth that is covered in glacial ice; which ice contains seventy-five percent of the world's fresh water supply. Glaciers cover over fifteen million square kilometers and they can be over four thousand two hundred meters thick in some places. Evolutionists believe that it takes millions of years to form glaciers and the creationists believe that the ice age glaciers were made within a few hundred years from the snow pouring down during and following the flood of Noah.
10% today

There is clear evidence for severe climatic fluctuations in earth's history resulting in the formation of vast glaciers. However, uniformitarian scientists have failed to recognize the occurrence of the global flood, and the effects of this event. The geologic ages and ice ages, which are believed by evolutionists to have occurred over vast periods of time were actually formed as a result of the Biblical flood.

* What is the division of geologic time in which many geologists place the last ice age?
Pleistocene Epoch * Know the location of the world’s major ice sheets today.
Most ice today is located in Antarctica and Greenland but some is also found in Canada, Alaska, California, Asia, and New Zealand. Most impressively though are the glaciers still found in the equatorial regions like South America's Andes Mountains and Mount Kilimanjaro in Africa. * Know the different types of glaciers (i.e., valley [alpine], ice sheets, piedmont, ice caps) and be able to describe each (generally). Give examples of each.
Alpine: Alpine Glacier - Most glaciers that form in a mountain are known as alpine glaciers. There are several subtypes of alpine glaciers
Piedmont: when multiple valley glaciers come together as one at a large stretch of flat line, the resulting mass is a piedmont glacier
Ice sheets: the largest of any glacier type, extending over 50,000 square kilometers. The only places on earth that have these frozen monsters are Antarctica and Greenland. Antarctica alone is home to 92% of all glacial ice worldwide. Ice sheets are so massive and heavy that they literally bend the continental crust on which they sit, a phenomena known as isostatic depression.
Ice caps: similar to an ice sheet, though smaller and forming a roughly circular, dome-like structure that completely blankets the landscape underneath.

* Know the difference between the zone of accumulation and the zone of wastage in a glacier. What is the “budget of the glacier”? If accumulation exceeds wastage, what happens to the glacier? What about if wastage exceeds accumulation? What if the two are equal?
Accumulation: the area above the firn line, where snowfall accumulates and exceeds the losses from ablation, (melting, evaporation, and sublimation). The annual Glacier equilibrium line separates the accumulation and ablation zone annually. The accumulation zone is also defined as the part of a glacier’s surface, usually at higher elevations, on which there is net accumulation of snow, which subsequently turns into firn and then glacier ice. Part of the glacier where snow builds up and turns to ice moves outward from there.
Wastage: the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass due to melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, avalanche, and any other ablation. The equilibrium line altitude (ELA) or snow line separates the ablation zone from the higher-altitude accumulation zone. The ablation zone often contains meltwater features such as supraglacial lakes, englacial streams, and subglacial lakes. The seasonally melting glacier deposits much sediment at its fringes in the ablation area. Ablation constitutes a key part of the glacier mass balance.
The amount of snow and ice gained in the accumulation zone and the amount of snow and ice lost in the ablation zone determine glacier mass balance. Often mass balance measurements are made in the ablation zone using snow stakes.
Budget: Glaciers also display a "movement" called advance and retreat. Though not technically movement in the same sense as plastic flow and basal slip, these apparent motions are much more easily seen over long periods of time. The phenomena that cause the advances and retreats are the actual motions coupled with the rates of addition and loss of ice in the glacier. The balance of these things is called the GLACIAL BUDGET.

We will consider an alpine glacier as an example. All ice is added as snowfall. In the lower stretches of an alpine glacier as much snow melts during the summer as fell during the preceding winter, as well as an additional amount of ice that had accumulated in earlier winters. If this were not so the glacier would be infinitely long! This part of the glacier that experiences net loss or ABLATION of ice is called the ZONE OF ABLATION. In the higher elevations the reverse is true. Temperatures remain low enough even in the summer that less snow melts in summer than falls in winter and so there is net addition or ACCUMULATION of ice at the upper end. This is called the ZONE OF ACCUMULATION.

If the amount of accumulation in a given year (or longer period) is greater than the amount of ablation, the upper end of the glacier gains mass and causes the entire mass to move downhill faster than before. If this pushes the end faster than ablation can remove ice from it the glacier will ADVANCE, or move its end farther down valley.

If, on the other hand, the amount of ice added at the top is lower, the glacier's mass will decline and it will move downhill more slowly. This may allow the end to melt faster than it can be replaced, causing the glacier to RETREAT. Please note that the ice does not move back uphill. the retreat is entirely because the ablation rate is higher than the rate of advance. The ice still moves downhill.

* Be able to describe the major flow mechanisms operating in a glacier (i.e., plastic flow and basal slip [i.e., slipping along its lower surface where it contacts the land surface]).
Basal: the act of a glacier sliding over the bed before it due to meltwater under the ice acting as a lubricant. This movement very much depends on the temperature of the area, the slope of the glacier, the bed's sediment size, the amount of meltwater from the glacier, and the glacier's size.

The movement that happens to these glaciers as they slide is that of a jerky motion where any seismic events, especially at the base of glacier, can cause movement. Most movement is found to be caused by pressured meltwater or very small water-saturated sediments underneath the glacier. This gives the glacier a much smoother surface on which to move as opposed to a harsh surface that tends to slow the speed of the sliding. Although meltwater is the most common source of basal sliding, it has been shown that water-saturated sediment can also play up to 90% of the basal movement these glaciers make.

The most activity seen from basal sliding is within thin glaciers that are resting on a steep slope, and this most commonly happens during the summer seasons when the sun melts away some of the exposed glacier. Factors that can slow or stop basal sliding relate to the glacier's composition and also the surrounding environment. Glacier movement is resisted by debris, whether it is inside the glacier or under the glacier. This can affect the amount of movement that is made by the glacier by a large percentage especially if the slope on which it lies is low. The traction caused by this sediment can halt a steadily moving glacier if it interferes with the underlying sediment or water that was helping to carry it.
Plastic: ...shear stress or force is applied to a sample of ice for a long time, the sample will first deform elastically and will then continue to deform plastically, with a permanent alteration of shape. This plastic deformation, or creep, is of great importance to the study of glacier flow. It involves two processes: intracrystalline gliding, in which the layers within an ice crystal shear parallel to...

* Know the difference between abrasion and plucking.
Abrasion: glacier sloughs surface of land… Plucking: glacier picks up pieces of sediment/rock

* Name and describe the erosional features in glacial terrain: glacial striations, glacial trough, hanging valleys, cirques, arêtes, horns, and fiords.
Glacial striation: scratches or gouges cut into bedrock by glacial abrasion
Glacial trough: A deep U-shaped valley with steep sides that leads down from a cirque and was excavated by a glacier.
Hanging valley: a valley that is cut across by a deeper valley or a cliff
Cirque: a cirque is a bowl shaped hollow at the head of a valley. Within a cirque lies a snowfield, the place where snow accumulates to form a cirque glacier.
Aretes:a sharp mountain ridge
Horn: sometimes in its most extreme form called a glacial horn, is an angular, sharply pointed mountain peak which results from the cirque erosion due to multiple glaciers diverging from a central point.
Fiords: a long, narrow, deep inlet of the sea between high cliffs, as in Norway and Iceland, typically formed by submergence of a glaciated valley.

* Name and describe the depositional features in glacial terrain: lateral and medial moraines, end moraines, ground moraines, eskers, kames, drumlins, kettles, and outwash plains/valley trains.
Lateral: parallel ridges of debris deposited along the sides of a glacier. The unconsolidated debris can be deposited on top of the glacier by frost shattering of the valley walls and/or from tributary streams flowing into the valley. The till is carried along the glacial margin until the glacier melts. Because lateral moraines are deposited on top of the glacier, they do not experience the postglacial erosion of the valley floor and therefore, as the glacier melts, lateral moraines are usually preserved as high ridges.
Medial: A medial moraine is a ridge of moraine that runs down the center of a valley floor. It forms when two glaciers meet and the debris on the edges of the adjacent valley sides join and are carried on top of the enlarged glacier. As the glacier melts or retreats, the debris is deposited and a ridge down the middle of the valley floor is created. The Kaskawulsh glacier in the Kluane National Park, Yukon, has a ridge of medial moraine 1 km wide
End: are ridges of unconsolidated debris deposited at the snout or end of the glacier. They usually reflect the shape of the glacier's terminus. Glaciers act much like a conveyor belt, carrying debris from the top of the glacier to the bottom where it deposits it in end moraines. End moraine size and shape are determined by whether the glacier is advancing, receding or at equilibrium. The longer the terminus of the glacier stays in one place, the more debris accumulate in the moraine. There are two types of end moraines: terminal and recessional. Terminal moraines mark the maximum advance of the glacier. Recessional moraines are small ridges left as a glacier pauses during its retreat. After a glacier retreats, the end moraine may be destroyed by postglacial erosion
Ground: Ground moraines are till-covered areas with irregular topography and no ridges, often forming gently rolling hills or plains. They are accumulated at the base of the ice as lodgment till, but may also be deposited as the glacier retreats. In alpine glaciers, ground moraines are often found between the two lateral moraines. Ground moraines may be modified into drumlins by the overriding ice.
Eskers: a long ridge of gravel and other sediment, typically having a winding course, deposited by meltwater from a retreating glacier or ice sheet
Kames:a steep-sided mound of sand and gravel deposited by a melting ice sheet
Drumlins: a low oval mound or small hill, typically one of a group, consisting of compacted boulder clay molded by past glacial action.
Kettles: a shallow, sediment-filled body of water formed by retreating glaciers or draining floodwaters.
Outwash plains/valley trains: a plain formed of glacial sediments deposited by meltwater outwash at the terminus of a glacier

* What is the zone of fracture in a glacier? How deep is this zone?
The top 50 metres (160 ft) of a glacier are rigid because they are under low pressure. This upper section is known as the fracture zone; it mostly moves as a single unit over the plastically flowing lower section. When a glacier moves through irregular terrain, cracks called crevasses develop in the fracture zone. Crevasses form due to differences in glacier velocity. If two rigid sections of a glacier move at different speeds and directions, shear forces cause them to break apart, opening a crevasse. Crevasses are seldom more than 150 feet (46 m) deep but in some cases can be 1,000 feet (300 m) or even deeper. Beneath this point, the plasticity of the ice is too great for cracks to form. Intersecting crevasses can create isolated peaks in the ice, called seracs. * Describe glacial calving. Where does it occur? is the breaking off of chunks of ice at the edge of a glacier.[1] It is a form of ice ablation or ice disruption. It is the sudden release and breaking away of a mass of ice from a glacier, iceberg, ice front, ice shelf, or crevasse. The ice that breaks away can be classified as an iceberg, but may also be a growler, bergy bit, or a crevasse wall breakaway.
Calving of glaciers is often accompanied by a loud cracking or booming sound[3] before blocks of ice up to 60 metres (200 ft) high break loose and crash into the water. The entry of the ice into the water causes large, and often hazardous waves.[4] The waves formed in locations like Johns Hopkins Glacier can be so large that boats cannot approach closer than 3 kilometres (1.9 mi). These events have become major tourist attractions in locations such as Alaska

* Know the definitions of the terms glacial drift, till, and stratified drift. How do these relate to one another?
Glacial drift: material transported and deposited by glacial action. Note that most glacial features are recessional, i.e., they are formed by retreating ice. Materials deposited during glacial advance are usually overridden and destroyed or buried before the glacier has reached its maximum.
Till: unstratified drift (e.g., material not organized into distinct layers), ice-transported, highly variable, may consist of any range of particles from clay to boulders. Ice-deposited material is indicated by random assemblage of particle sizes, such as clay, sand and cobbles mixed together. Ice-worked material is indicated by sharp-edged or irregular shaped pebbles and cobbles, formed by the coarse grinding action of the ice.
Stratified drift: Fluvioglacial drift composed of material deposited by a meltwater stream or settled from suspension

Deserts (Chapter 4)

* What is the difference between desert and steppe climates?
A steppe climate is found in the middle of continents and in the lee of high mountains. The mountains block moist air from oceans or tropical climates from reaching the steppe. There is not enough precipitation for trees to grow except by rivers. The plants have adapted to these drought conditions by being small and growing extensive root systems. Animals have adapted by burrowing into the ground to stay cool or warm, and to find protection on the open plains of the steppe.
The temperature between summer and winter varies a lot. Summer temperatures of the steppe aren't much different from the dry savanna. Both are grasslands, and both can reach temperatures of 104° F, and have heavy thunderstorms. In the winter, however, there are no clouds to keep heat from escaping into the upper atmosphere. The land gets colder and colder. Winter temperatures of -40° F are not uncommon. There are no trees to block the wind, so it howls. The combination of low temperatures and dry winds make it a very harsh place to live. A little less rain and steppe could be desert. * What is the most important erosional agent in a desert environment? * Know the geographic distribution of deserts around the world. See SmartFigure 4.24 on page 137. How much of the world is covered by deserts? * Be able to define the following terms: ephemeral stream, alluvial fan, bajada, and playa lake. * What is deflation? How does this relate to desert pavement? * What is loess? What is its origin? * Describe sand dunes and how they form.

Plate Tectonics (Chapter 5)

* Who proposed the hypothesis of continental drift? What did he call his proposed supercontinent? * What physical and geological evidences support continental drift? * Why was continental drift largely rejected by the scientific community in the early 20th century? * Know what glossopteris and mesosaurus are. How are these important to the continental drift hypothesis? * Be able to define lithosphere and asthenosphere. How do the two differ? * What are the relative densities of oceanic and continental crust (i.e., which is denser)? * Be able to define the following: divergent boundary, convergent boundary, and transform fault boundary. Know what happens at each of these boundaries in terms of plate interaction, seafloor production/destruction, volcanism, and earthquake activity. Also, know what kinds of geologic features form at each type of boundary. Finally, how does the presence of both divergent and convergent boundaries help explain the fact that the earth is neither growing in size nor shrinking in size? * What is a subduction zone? * What is a hot spot? How are these evidence of plate tectonics? * Know what the Pacific Ring of Fire is. * Be able to name and describe the forces that drive plate motion (i.e., slab pull, ridge push, and mantle drag). * What is a mid-ocean ridge? Know the average rate of seafloor spreading at an ocean ridge. * Know how age of the ocean crust and depth of ocean sediment relate to distance from the mid-ocean ridge. * Who were the scientists who first studied (comprehensively) magnetic striping in oceanic crust? What did they find?

Geologic Time (Chapter 8)

* According to Lutgens and Tarbuck (and other secular geologists), how old is the earth? * Define uniformitarianism and catastrophism. How do they differ? Who is responsible for proposing the idea of uniformitarianism? * What is an unconformity? * Be able to name and describe the three basic types of unconformities (i.e., angular unconformity, disconformity, and non-conformity). * Be able to describe the principle of superposition, the principle of original horizontality, the principle of cross-cutting relationships, and the principle of fossil succession. * Name the conditions that favor fossil preservation. * Be able to describe the different types of fossils, premineralization, molds and casts, carbonization fossils, and trace fossils. * What is an index fossil? What are the essential characteristics of an index fossil? * Define correlation. How are fossils used to correlate sedimentary rocks across large geographical areas? * Define parent elements and daughter elements in terms of radioactive decay processes. * Be able to describe the three basic types of radioactive decay: alpha, beta, and electron capture. You must be able to speak of these in terms of the change in atomic number and atomic mass when the parent element decays. For example, alpha particle decay reduces the atomic number of a parent element by 2 and reduces the atomic mass by 4. See Figure 8.17 on page 284. * Know the half-lives of common radioisotopes such as uranium-238, uranium-235, potassium-40, rubidium-87, and carbon-14. See page 286 for assistance. * Which rock types can and cannot be dated using radiometric methods? * If given the half-life of a radioisotope AND the number of years that have passed since radioactive decay processes began, be able to determine 1) the number of half-lives that have passed and 2) the amount of the parent element remaining. For instance, if you are told the half-life of carbon-14 is 6,000 years and the decay process started 6,000 years ago, then you could say that 1) only one half-life has passed and 2) about 50% or one-half of the parent isotope remains. Use SmartFigure 8.19 on page 285 for assistance. * Know the basic structure of the geologic time scale. You do not have to memorize the scale, but you need to know what eons, eras, periods, and epochs are, and how long they are relative to one another (i.e., eons are longer than periods, epochs are shorter than eons, etc.). The largest defined unit of time is the supereon, composed of eons. Eons are divided into eras, which are in turn divided into periods, epochs and ages. The terms eonothem, erathem, system, series, and stage are used to refer to the layers of rock that correspond to these periods of geologic time in earth's history.

* Geologists qualify these units as Early, Mid, and Late when referring to time, and Lower, Middle, and Upper when referring to the corresponding rocks. For example, the Lower Jurassic Series in chronostratigraphy corresponds to the Early Jurassic Epoch in geochronology.[3] The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus "early Miocene" but "Early Jurassic." * Know the basic definitions of the three most recent geologic eras: Paleozoic, Mesozoic, and Cenozoic. What do each of these mean (i.e., Mesozoic means “middle life”)? * What is the Precambrian? How much time do secular geologists say the Precambrian covers? of, relating to, or denoting the earliest eon, preceding the Cambrian period and the Phanerozoic eon. the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale. It spans from the formation of Earth about 4600 million years ago (Ma) to the beginning of the Cambrian Period, about 541.0 ± 1.0 Ma, when macroscopic hard-shelled animals first appeared in abundance. The Precambrian is so named because it precedes the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the classical name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of geologic time. * What are some difficulties in dating the geologic time scale? * Who was James Ussher? How old did he say the earth is? was Church of Ireland Archbishop of Armagh and Primate of All Ireland between 1625 and 1656. He was a prolific scholar, who most famously published a chronology that purported to establish the time and date of the creation as the night preceding Sunday, 23 October 4004 BC, according to the proleptic Julian calendar.
Morris Textbook (Chapters 1–2, 4–5, and 7): * How are human beings limited in their ability to interpret the past, according to Morris? * Does the Bible interpret the Hebrew word “yom”? If so, what does “yom” mean? Yom means day * Know the difference between young-earth creationists and old-earth creationists? On what major point do they differ? * What is meant by “overlapping days” in Genesis? Is this an old-earth or young-earth viewpoint? What are some weaknesses in it? Young earth * How does Morris use tree rings and Niagara Falls in Chapter 4 to make his point about uncertainty in the geologic past? In what ways can Niagara Falls be used to support a young-earth model? * Know and understand (generally) the four assumptions that underlie radiometric dating methods. * How does the supposed radiometric age of the Cardenas Basalt in the Grand Canyon as compared to the supposed radiometric age of the basalts on the canyon rim (i.e., the plateau basalts) bring into question the geologic history of the Grand Canyon? * What are radiohalos, and how do they support a young earth? * Why is carbon-14 dating not reliable for materials more than a couple thousand years old? * How does helium in the atmosphere help explain a young earth? * How do old-earth geologists and young-earth geologists differ on the idea of “remnant magnetism” and magnetic reversals? * What are the input and output processes related to the salinity (i.e., salt concentrations) in the modern ocean? How do creation scientists use the salinity of the ocean to bolster the case for a young-earth? * In general, how does erosion of the continental rocks and deposition of the resulting sediment in the ocean support a young-earth model?