Austin Pope
Lesson 17 Exercise
29 April 2015

1. What do the various kinds of rocks used for monuments tell us about weathering?
There are three principal types of stone used in the structures, pedestals, and ornament of the many monuments that may be found throughout the parks system: granite, limestone, and marble.
Granite, an igneous rock, is formed through the cooling and crystallization of molten bodies within the earth. It is dense and durable. Limestone is a sedimentary rock comprised mainly of the mineral calcite and formed through the compression of mostly marine organisms in pre-historic times. It can be soft and flinty and porous and, though easy to cut and tool, it is susceptible to weathering from the effects of acid rain and other pollutants. Marble is created through a metamorphic process in which heat and pressure cause the recrystallization of sendimentary carbonate rocks, and is related to limestone. It is often prized for its variegated color and veining, but may also be found in a pure white. Most marble, especially the colorful variety, is actually limestone, though commercial quarries and vendors, unlike geologists, tend to distinguish the two. Marble is also highly vulnerable to damage from weathering and pollutants. As used in monuments, the same granite and marble may have a strikingly different appearance and coloration depending on whether their surface treatment has a flame finish, honed surface, or polished treatment.

2. What rock-forming minerals found in igneous rocks weather to clay minerals?
Clay minerals are produced as residual minerals during the weathering of feldspars and Micas.

3. How does abundant rainfall affect weathering?
Rainfall and temperature can affect the rate in which rocks weather. High temperatures and greater rainfall increase the rate of chemical weathering. Rocks in tropical regions exposed to abundant rainfall and hot temperatures weather much faster than similar rocks residing in cold, dry regions.

Austin Pope
Lesson 17 Exercise
29 April 2015

4. Which weathers faster, a granite or a limestone?
Limestone because of its mineral property, which is composed of mainly calcite which is weaker than granite and the minerals it usually is made up of, quartz, feldspar, mica.

5. How does physical weathering affect chemical weathering?
Physical weathering increases the surface area that can be attacked by chemical weathering.

6. How do climate affect chemical weathering
Humidity and temperature are the keys to chemical weathering .Chemical weathering needs water, to act as a solvent and to transport corrosive ions so chemical weathering in arid climates, and in arctic climates (where water is frozen, and so not available) have little if any chemical weathering. Chemical processes are also (mostly) accelerated by higher temperature so the high humidity and high temperature of the tropics is the place where chemical weathering predominates. Contribution of humic acids from soils is also important, and the high rate of growth of plants in tropical climates is also a factor.

7. What role do earthquakes play in the occurrence of landslide?
Earthquakes are commonly triggers, providing energy that causes a slope to fail.

8. What kinds of mass movements advance so rapidly that a person could not outrun them?

Avalanches. Lahars, Neue Ardentes or pyroclastic flows,and rockfalls,

Austin Pope
Lesson 17 Exercise
29 April 2015

9. How does the absorption of water weaken unconsolidated material?
Unconsolidated materials are those that have not been packed and/ or pressed by any natural or human means, allowing small pockets of air going in and out of the material in question. The water absorption occurs by direct contact or by the condensation of moisture in the air, a process of oxidation occurs and oxygen is released into the atmosphere, leaving an empty space in the basic structure of the material in question. With time, the material degrade.

10. What is the angle of repose and how does it vary with water content?
Angle of repose is the steepest angle that unconsolidated material naturally rests. Very wet sediment angle < slightly wet sediment angle < very wet sediment angle.

11. How does the steepness of a slope affect mass wasting?
In unconsolidated material, the steeper the slope, the greater the risk for mass wasting, all other factors being equal. In consolidated materials, there is little mass wasting most of time, but joints and faults can increase the likelihood, and earthquake can act triggers. When steep consolidated material is wasted, it is rapid and dangerous.

As slope gets steeper, the shear stress component get larger relative the friction component, leading to failure. Consolidated slopes can be very steep before they fail, whereas unconsolidated slopes usually fail at less steep angles.

Austin Pope
Lesson 17 Exercise
29 April 2015

12. What is a mudflow, and how it is produced?
Mudflow alludes to a stream of water that contains a lot of suspended particles and sediment. It has a higher density and viscosity than a streamflow and can store just the coarsest part of its heap; this reasons irreversible silt entrainment. Its high density and viscosity won't permit it to stream similarly as a water stream.
Mudflows happen on steep slopes where vegetation is not sufficient to avert quick erosion but rather can happen on gentle slopes if different conditions are met. Different components are substantial precipitation in brief times and an effortlessly erodible source material. Mudflows can be produced in any climatic administration yet are most basic in bone-dry and semiarid regions. They may surge down a mountainside at velocities as awesome as 100 km (60 miles) every hour and can bring about extraordinary harm to life and property. Boulders as large as houses have been moved by mudflows.Mudflow stores are inadequately sorted mixtures of ilt, boulders, organic materials, and other debris. They have sudden and very much characterized edges, sporadic surfaces, and a lobate appearance; they may be 3 to 6 m (10 to 20 feet) high. Such stores are far reaching on alluvial fans and around the bases of numerous volcanoes

Austin Pope
Lesson 17 Thought Questions
29 April 2015

1. In Northern Illinois, you can find two soils developed on the same kind of bedrock: one is 10000 years old and the other is 40000 years old. What differences would you expect to find in their compositions or profiles?
In Northern, the old, upland soils are mostly Mollisols and Alfisols, with an occasional Spodosol up north and Histosols scattered about in low spots.

* The central concept of Mollisols is that of soils that have a dark colored surface horizon and are base rich. Nearly all have a mollic epipedon. Many also have an argillic or natric horizon or a calcic horizon. A few have an albic horizon. Some also have a duripan or a petrocalic horizon.

* The central concept of Alfisols is that of soils that have an argillic, a kandic, or a natric horizon (prominent B) and a base saturation of 35% or greater. They typically have an ochric epipedon, but may have an umbric epipedon. They may also have a petrocalcic horizon, a fragipan or a duripan.

* The central concept of Spodosols is that of soils in which amorphous mixtures of organic matter and aluminum, with or without iron, have accumulated. In undisturbed soils there is normally an overlying eluvial horizon, generally gray to light gray in color, that has the color of more or less uncoated quartz. [bleached E horizon]
Most Spodosols have little silicate clay. The particle-size class is mostly sandy, sandy-skeletal, coarse-loamy, loamy, loamy- skeletal, or coarse-silty.

* The central concept of Histosols is that of soils that are dominantly organic. They are mostly soils that are commonly called bogs, moors, or peats and mucks.
A soil is classified as Histosols if it does not have permafrost and is dominated by organic soil materials

2. Which igneous rock would you expect to weather faster, a granite or a basalt? What factors influence your choice?
The basalt will chemically weather faster since granite contains quartz which is not chemically weathered. Also, granite is used for headstones and does not chemically weather fast.

Austin Pope
Lesson 17 Thought Questions
29 April 2015

3. Assume that a granite with crystal about 4mm across and a rectangular system of joints spaced about 0.5 to 1m apart is weathering at Earth’s surface. What size would you ordinarily expect the largest weathered particle to be?
Mean joint spacing appears to decrease from fresh, through slightly and moderately weathered granitic rock, then increases from moderately weathered rock, through highly and completely weathered granitic rock. The widest joint spacing occur in either fresh or completely weathered rock, and the closest, in moderately weathered rock. Mean joint trace lengths decrease from fresh rock to slightly weathered rock, increase in moderately weathered rock, then appear to shorten from moderately weathered rock through highly and completely weathered granitic rock. The shortest mean trace lengths occur in completely weathered granitic rock, and the longest, in moderately or highly weathered rock.

4. Why do you think a road built of concrete, an artificial rock , tends to crack and develop a rough, uneven surfaced in a cold, wet region even when it is not subjected to heavy traffic?

Freezing-thawing damage is a major degradation mechanism for concrete structures in cold regions. This damage becomes more severe when coupled with deicing salts application.

5. Pyrite is a mineral in which ferrous iron is combined with sulfide ion. What major chemical process weathers pyrite?

It might weather by oxidation. After it is oxidized it might form hematite, magnetite, and sulphate minerals.

6. Rank the following rocks in the order of the rapidity with which they weather in a warm, humid climate: a sand stone made of pure quartz, a limestone made of pure calcite, a granite, a deposit of rock salt (halite, NaCl).
Most rapid to most slow: Halite, limestone, arkose, granite, sandstone, quartz.,

7. What would a world look like if there were no weathering at the surface?
Without weathering, geologic features would build up but would be less likely to break down.

Austin Pope
Lesson 17 Thought Questions
29 April 2015

8. Would a prolonged drought affect the potential for landslide? How?

Yes. Landslides are caused by disturbances in the natural stability of a slope. They can happen after heavy rains, droughts, earthquakes or volcanic eruptions.

9. What geological conditions might you want to investigate before you bought a house at the base of a steep hill of bedrock covered by a thick mantle of soil

Geological conditions such as dip of bedding planes, fault plane, slope and nature of Earth material. The bedding planes of the bed rocks dip away from the slope and slope that is composed of igneous rock should be relatively stable.

10. What evidence would you look for to indicate that a mountainous area had undergone a great many prehistoric landslide?

Poorly vegetated scars where the slide turned loose, Deposits of fine to very coarse or mixed particles size materials at the base of the slope where the flow lost energy.

11. What factors would make the potential for mass movements in mountainous terrain in the rainy tropics greater or lesser than the potential in a similar terrain in a desert?

Soil saturation, or if the rainfall rate is greater than the rate at which water can infiltrate into the soil, surface runoff occurs. If the runoff has sufficient flow energy, it will transport loosened soil particles (sediment) down the slope.

12. What kind(s) of mass movements would you expect from a steep hillside with a thick layer of soil overlying unconsolidated sands and muds after a prolonged period of heavy rain?
Mass Wasting

Austin Pope
Lesson 17 Thought Questions
29 April 2015

13. What factors weaken rock and enable gravity to start a mass movement?
Physical weathering breaks down rock. Water, rivers, frost, plants, animal activity, changes in temperature are examples. Chemical weathering also has an impact also. Oxidation, dissolution, carbonation and acid rain are examples.