Which river does NOT begin in the Champaign Urbana area. * Sangamon River
CHAPTER 6, 11, 12, 14 * Flood probability is constant over time while risk of future eq is very low right after major eq and then will increase slowly as pressure builds
CLIMATE CHANGE
Climate- Long term average of daily weather conditions.
Extremes
* Early Earth = Very Warm * End of Paleozoic = Very Cold * End of Mesozoic = Very Cold * End of Ceonzoic = climate oscillations from very cold to very ward
Importance of Studying Climate Change A.) Effect on sea level- * If current glaciers were to melt, that water would drain into oceans and cause sea levels to rise (result in flooding) Alternatively if glaciers were to become much larger, water from oceans gets transferred to ice on leand and reduces sea level B.) Large Change in Climate- * If significant global warming occurs, some areas will become much drier (others wetter) causing deserts and also possibly worse severe weather and greater disease. If glaciers advance over large areas, it will force some people to migrate C.) Glaciers’ effect on landscapes/floods- * formed great lakes, flattens landscapes in other areas, rich soil of Midwest due to deposition of glacial debris. Can cause catastrophic floods. D.) Predict Future Climate- * Understand geologic past to help predict future (Inverse uniformitarianism)

* Gas by abundance * Nitrogen, Oxygen, Argon, Carbon Dioxide, Others * All objects emit e-m radiation, nature of which depends on their temperature. With > temperature, object emits > amount of radiation (> intensity) with shorter wavelength. Sun (surface temperature = 6,000°C) emits much of its energy as visible light. Earth is much cooler and emits much less radiation (lower intensity), ~ entirely as longer wavelength infrared radiation * Greenhouse effect- Some of incoming sunlight gets absorbed by Earth then is reradiated as longer wavelength heat radiation. Heat absorption raises average temperature of Earth and makes earth habitable. * Without Greenhouse effect, avg temperature on Earth would be 33 degrees C colder and water would be frozen. * ABUNDANCE OF CO2 IN ATMOSPHERE HAS MAJOR EFFECT ON GLOBAL TEMPERATURE
What processes affect abundance of CO2 in atmosphere? 1. Volcanism- Volcanic eruptions release gas as well as lave and volcanic ash. Volcanic eruptions are source of most gases in atmosphere (except o2) 2. Chemical Weathering 3. Burning Fossil Fuels 4. Photosynthesis (Increasing amount of plant life means less co2 in atmosphere 5. Respiration- reverse of photosynthesis reaction
Early Earth- CO2 abundance = 98%, P (bars)= 60, Avg Temp= 290 C
Current Earth- co2 abundance = .04%, P (bars) = 1, Avg Temp= 16 C A. End of Mesozoic/beginning of Cenozoic- very warm interval, resulted in flooding of much land on continents. Major reasoning is greater levels of co2 gas from greater volcanism by rapid seas floor spreading associated with opening of Atlantic Ocean. B. Cenozoic Cooling – after hot house climate, Earth cooled progressively. Major reason was related to plate tectonics.
General Controls on Climate A.) Atmosphere Composition- Ashfall eruptons can send enormous amount of volcanic ash into stratosphere for months to years. Dust reflect sunlight and can case short term cooling. Geologic example = Tambora Indonesia volcanic erupton of 1815. Cooled temp and worldwide temp resulted in 90000 deaths. B.) Sun Intensity- as glaciers enlarge, more sunlight is reflected and makes Earth even colder.
Variations in Earth’s orbit and spin/rotation- this effect on solar energy is used to explain regular oscillations of icehouse and warmhouse climates.Today glacier coverage = 10% during ice age = 30%
How are 20 periodic fluctuations in global climate explained? 1. Shape of Earth’s orbit- varies from circular to elliptical on 100,000 year scale 2. Woble of Earth’s axis- earth wobbles on its spin axis with 23,000 year cycle. 3. Tilt of Spin axis- 41,000 yr cycle. Greater variation in seasons with highest tilt.

C.) Distribution of Land ad water masses D.) Wind/atmospheric circulation E.) Ocean circulation- controlled by global wind patterns, but also influence by land and water mass distribution. F.) Mountains

COASTAL EROSION
Coastlines- where land meets bodies of water. Beaches= Earth’s most dynamic environment due to continuous erosion, transport + deposition of sediment…they can undergo great changes during single storm or from gradual change. (only problem for people that live in environment)
Coastal Hazards= hurricanes, tsunamis, coastal erosion. Human intervention often occurs to protect developed areas from coastal erosion however measure often fail
Coastal processes- most important process in coastal areas is action of waves. Lesser importance = tides
Wave terms: * Crest= top of wave ; Trough=lowest point ; Wave length=horizontal distance from crest to trough ; wave height= vertical distance from crest to trough ; wave period= amount of time fro one complete wavelength to pass given point. * Waves with long wavelength and large wave period are most powerful and erosive. In opern water, water molecule in wave moves in CIRCULAR trajectory that DECREASES with depth. Water is motionless at depth great then .5 x Wave length. Eventually wave top outruns bottom and collapses into surf zone where for ward and backward motion occurs (this is what drive sediment movement) * Wave fronts= lines along crest + wave normal. Wave refraction = bending of wave fronts as one part of wave reaches shallow water before another part. Even with wave refraction, water surges up beach at small angle to coastline + retreat backward due to gravity and creates zig –zag motin = swash + backwash. Typical angle of approach is less than 5 degrees (not parallel to coast). Transported sediment = longshore drift. * Curved coastlines are common. Wave recation will focus wave energy at protduing headlines causin erosion and cliff formation. Efect of wave recratio = straighten coastlines.
Features of Beaches 1. Spit – finger like ridge of sediment that extend into depper water due to longshore currents (E.g. Cape Cod) 2. Barrier Islands – elongate, low relief, very long islands of sand parallel to coast; (long Island) great for recreation but bad for permanent development 3. Sea Cliffs – wave erosion can undermine cliff, causing landslides. Avoiding building near
Problem – many nations in world have coastal zones; 30/50 states have coastlines along major water body. Coastal erosion is an ongoing, gradually developed geologic hazard in USA
Causes of large- scale coastal erosion a. Glorbal rise in sealevel b. Dams- traps sediment before it reaches coastlines
Prediction of Coastal erosion- Very complex and hard to produce successful results of mitigation.
Mitigation of Coastal erosion- accelerating coastal erosion has led to many efforts to prevent erosion. Many fail 1. Seawalls- onshore wall of concrete of rock debris parallel to coastline. Purpose= protect land behind wall from wave energy but commonly fail. (Ex: Galveston TX) 2. Groins- wall of concrete, rock, wood, or sanbags built perpendicular to beach to trap moving sand and widern beach. Usually successful on upcurrent side but supply for downcurrent side of beach is cut off and erosion occurs down there. 3. Jetties- pair of long groins that protect harbor channel from sedimentation. Because of size, jetties completely cut off longshore sediment transport, problem of upcurrent deposition + downcurent erios greather than for groins

Which sediment type is better to prevent water from flowing through levee, sand, or mud?
Mud- low permeability (water flows through it VERY slowly)