Chapter 2- terms/Study guide for test (Earth Science)

Cross Beds

(a sedimentary structure) reflect transport (they preserve the internal structure of dunes and ripples). They also show ripple/dune migration through time, and can indicate changes in current direction. Important: cross beds lean in to the direction that current was coming from. These form in rivers and deserts (and may be preserved on lake shores, as well).

Chemical Weathering

(change in chemical structure or properties): minerals formed at depth are less stable at surface pressures and temperatures (STP), and will react with things in their environment (air and water) to produce more stable minerals.

What percentage of freshwater is in rivers and lakes?

.03 percent

How can we prevent future slope failure?

1. )Hazard mapping and zoning restrictions 2.) Revegitation (holds slopes together), 3. Regrading, stabilized slopes(getting closer to angle of repose). 3. Reinfocement (rock bolts, rock nets), and improved range. 4. Add drainage - get water to move out of the slope 5. Soil bolting (limited Success)

What steps would you follow if you had to pick an organism and put it somewhere to maximize it's chances of becoming a fossil?

1. Be Robust and Have Hard Parts 2. Be Abundant ( and live a long time). 3. Get buried quickly ( be marine, or at least fall in a lake). 4. Get buried somewhere anoxic to avoid bacterial decay. 5. Things that get preserved: teeth, bones, shells, carapaces, woody parts of plants, spores, pollen, bias towards calcitic hard shelled organisms.

What different factors determine the soil type that forms in a region?

1. Climate (temperature and precipitation_) 2. Relief of ground surface 3. Nature/composition of parent material 4. Time to develop 5. Number and types of living organisms

What big assumptions do we make when we utilize radiometric dating?

1. It's a closed system (closure temp.) remember minerals are inorganic naturally occurring solids with a crystal structure and characteristic chemical composition. They cool and solidify at specific temperatures: they stop exchanging material with the enviornment. this closes the system and starts our radiometric clock. If you re-heat the rock above the closure temp you re-set the clock again, chemical weathering can also mess this up. 2. No daughter mater is present initially (or we know the amount) If you violate these assumptions you will get weir dates. If you do not violate these assumptions you get accurate ages.

Know how and why rounding, and mineral composition change with increasing time being transported in a clastic sedimentary system. What does this have to do with Bowen's Reaction Series?

1. Shape will: Grains will get rounded and smaller with increasing distance from the source (result of weathering). 2. Mineral composition will: All the stuff at high temp is less stable, so you will be left with the things that are more stable and farther down, quartz is super stable and most likely what you will end up with.

What are the two main ways by which humans impact flooding.

1. Urban vs. rural drainage: asphalt and concrete surfaces are impermeable, and cause runoff to spike rapidly after a storm. This shifts our hydrograph: stream discharge peaks higher and earlier than it would in a rural system. You should be able to recognize a hydrograph of a rural vs. an urban storm event for the second exam. 2. Climate change: for every __1__F increase in temperature, the atmosphere can hold __4___% more water. This is expected to lead to more frequent and more severe storms.

What factors interact to determine the size of waves?

1. Wind speed: How hard is the wind blowing? 2. Fetch: Over what distance is the wind blowing? 3. Duration: How long is the wind blowing for?

How do we predict slope failure?

1.) Record of past failures 2.) Changes in slope (undercutting, re-grading. 3.) Steep slopes 4.) Potential triggers: rainfall, volcanic activity, etc.

How much water do wee need to survive each day?

1.3 gallons of 5 L

What percentage of marine organisms have mineralized hard parts?

1/3

What is the average rate on coastal erosion in the United States?

2-3 feet each year

How Many Species are currently alive?

3,000,000 to 100,000,000

What percentage of the earths surface is covered by deserts and steppes?

30%

Average rate of sea-level rise over the past two decades.

3mm/yr

What is the annual economic cost of soil loss in the US?

44 billion dollars

What percentage of people in the united states use ground water daily.

44%

How much water on average do we use each day in the U.S.

4455 liters a day

Landslide (unconsolidated)

: material fails and initially moves along a well-defined plane (the landslide portion of the event), breaking up into a chaotic jumble as it continues downhill (the debris flow portion of the event).Landslides can turn into debris flows during single events due to addition of water and/or loss of sediment cohesion. They can also just stay landslides, but usually the materials break up.

Starting with dry particles, how will the angle of repose change as we add progressively more water?

A little bit of water increases particle cohesion which increases the angle of repose. Lots of water eliminates particle cohesion, decreases friction, and adds weights, which decreases the angle of repose.

Permiability

A measure of connectivity-how easy is it to transmit fluids? Granite has many fractures and has high permeability so does losely cemented gravels. Clay (shale) is compacted and has low permeability so does porus volcano rock with separate pores.

How do springs form>

A spring is formed when the pressure in an aquifer causes some of the water to flow out at the surface where the water table is intersected.

Absolute Dating

A technique used to determine the actual age of a fossil, gives a specific age, My Cat is 10, I ate that donut in 2010.

karst topography

A type of landscape in rainy regions where there is limestone near the surface, characterized by small by small ponds, disappearing streams, caves, and also sinkholes, and can also generate hills.

Seawalls

A way to armor the coast is as in Galveston, Texas). Build a big wall! Problem: you lose your beach. Energy is focused in front of the wall, and sand is eroded away.

How do we engineer rivers to flood less?

A. Channelization: concrete your channel. This allows the channel to hold more water, and water passes through areas rapidly. However, areas downstream experience increased erosion. B. Artificial Levees: these structures can keep rivers within their (now higher) banks during flood events. However, they are not fail-proof and are expensive to construct. C. Dams: these are useful to a point, but have short lifespans since they trap sediment, are expensive, and cannot stop all floods.

The different types of decay processes

Alpha decay, beta decay, and electron capture.

What is a drainage basin- what defines its edges?

An entire network plus its tributaries forms a drainage basin, which is bounded by topographic highs that create drainage divides.

Given an unconfined and confined aquifer which might require more pumping assuming that both wells were at the same depth?

An unconfined aquifer, because you need to drill and pump at the level of the water table this is where the highest water will rise. In a confined aquifer the water is under pressure due to the weight of the overlying rocks and sediment. Water will rise too the level of the potentiometric surface- this can give us artesian wells, which do not need to be pumped.

Revetments/ Ripraps

Another way to armor the coast:these are basically piles of rocks or interlocking concrete slabs that can be used to armor the beach. These are easy to install and maintain and physically do a good job of holding the shore in place. However, they do not protect structures behind the wall, which are still vulnerable during storm events.

If you had to build a highway by cutting into the middle of a geologic structure, would it be wiser to cut into an anticline or a syncline?

Anticline

What is a fossil?

Any remain, trace, or imprint of a plant or animal that has been preserved from some past geologic or prehistoric time. So anything that has died before we started writing things down, or died and left some kind of trace or track.

Beach Nourishment

Armor the coast: in these projects, sand is often pumped from offshore onto beaches. This does build a beach! Problem: it damages sea life, is wildly expensive, and that sand continues to leave like it did before, so you end up without a beach again pretty soon.

Jetties/ Groins

Armor the coast:shore-perpendicular structures that are used to protect harbors or accumulate sand. Sand accumulates up current, and these structures do successfully prevent the transport of sand down the beach. Problem: if you aren't moving sand down the beach, you get really bad erosion anywhere that lacks a jetty or groin.

Windward part of a mountain side.

As wind moves across the ocean towards Oregon, solar heating dries evaporation and air becomes very moist. When these warm wet air pockets hit costal oregon, they run into mountains. As air rises, it cools and condenses. Thus gives us precipitation of the windward side of the mountain.

What are our two kinds of stream morphologies, and how do they differ?

Braided Streams and Meandering Streams. Braided streams have multiple channels separated by islands and bars of sediments, while meandering streams have a single channel that curves back.

Where do we overdraw our groundwater budget in the United States?

California and the west

The periods in order- Can old senators demand more political power than juinor congressman? Tough Question

Cambrian, Ordovician, Silurian, Devonian, Missisipian, Pennsylvanian, Permian, Triassic, Jurassic, Cretaceous, Tertiary, Quaternary

What is the best material for radioactive dating and why?

Carbon, Every 5,730 years, the radioactivity of carbon-14 decays by half. That half-life is critical to radiocarbon dating. Since carbon-12 doesn't decay, it's a good benchmark against which to measure carbon-14's inevitable demise. The less radioactivity a carbon-14 isotope emits, the older it is

The order of appearance in the fossil record

Chemical to Trace to Body

Chemical Fossils

Different isotopes are easier to use metabolically/ incorporate into skeletal material, because they behave differently. As an example life prefers 12C over 13 C, so when we find isotopically light carbon rocks we can assume this is a chemical fossil of life since living animals have such a strong preference for one isotope over the other.

Law of inclusions

Each stratum is deposited from fluid upon a solid subjacent surface hard solid fossils may be incorporated into soft loose sediment at this stage. Anything incorporated within another rock bed or later has to be older than the rock it is stuck within.

T/F Iowa is the only state with no risk of mass wasting events.

False

What is a recurrence interval, how is it calculated, and could Colorado get another 100+ year flood this year?

Flood recurrence interval (R) R=(N+1)/m R=recurrence interval N=number of years on record M=rank of flood relative to highest annual flow for the time span we have records for With every new largest flood, the recurrence interval of the next largest event drops by approximately ______R= N + 1/m___________. NO?

How do evaporites form?

Form when water evaporates and leave minerals behind. Salt is an evaporite.

How do we learn about dinasour color?

Fossil Fathers preserve the melanin, the pigment that gives the color to the feather, so we can find the pigment in the feathers. The ink sacs are preserved in squids which can be used to determine pigment. Compare the shape and size of melnasome to the melanasomes in living birds feathers, allowing the interpretation and prediction of the color of these fossil feathers.

How do turbulent and laminar flow differ, and which is more common in actual streams?

In laminar flows, water molecules move in parallel lines, and keep their velocities. Turbulent flows do not move in parallel lines and experience changing velocities, these are more common in actual streams.

Do we see more physical or chemical weathering in deserts?

Mechanical weathering, low humidity results in very little chemical weathering.

Relative Dating

Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock. These are comparative statements. I am older than my cat, you are also older than that delicious donut.

Is any part of the US at risk for desertification? If so, where?

New Mexico, Texas, and Arizona.

Is there anywhere on Earth where we can observe, in a single outcrop, the complete record of earth history?

No

The epochs of the cenozoic oldest to youngest. People eat old milk playing plesant hollows.

Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, holocene.

Eras in order from oldest to youngest

Paleozoic, Mesozoic, and Cenozoic

Times at the boundaries

Precambian (541 MA), Paleozoic (252 MA), Mesozoic (66 MA), and Cenozoic (11.8 ka/ today).

ice wedging

Process that splits rock when water seeps into cracks, then freezes and expands. (Mechanical)

Half-lives

Proportion of parent atoms that turn into daughter atoms is the same in each half life: we always lose half of whatever we start the individual half life with. So if you started with 1,000 parent atoms after 1 half life you would have 500 parent atoms and so on.

What is the main erosional agents in deserts?

Running Water

Given our five different clastic rock types, be able to correctly order them from smallest grain size to largest grain size

Shale/Mudstone, siltstone, sandstone, conglomerate, breccia

Creep (unconsolidated)

Slow, continuous movement of material down slope. This is often related to freeze-thaw cycles and makes drunken trees.Thawing contraction: the water melts and the particles go straight down. Can do pretty significant damage to house and foundations.

Stratum is approximately horizontal

Strata deposited under the influence of gravity should form relatively flat beds. If you see a not flat bed something has happend.

How do stream discharge and stream stages differ in terms of what they are measuring?

Stream discharge is the measure of how much water is flowing past a point on the stream at any moment in time, where stream stages measure stream height against a reference point.

What is a losing Stream?

Streams in arid climates are frequently losing streams: water seeps out of them and downwards into the water table.

What is a gaining stream?

Streams in humid climates tend to gain water, the groundwater table is high enough that it releases water into the streams.

What do you do if you are caught in a rip current?

Swim diagonally to the coast.

What are the highest tide on earth, and how high are they?

The Bay of Fundy, exceeding 15 meters.

How do specific yield retention rate and specific retention rate relate to permeability and porosity?

The higher porosity the lower specific yield and specific retention rate, the lower porosity the higher specific retention rate and yield. The higher permiability the lower specific yield, and higher the retention rate and vice versa.

Base Level

The lowest point to which a stream can erode

What is longshore drift and how does it work?

The main way that waves move sediment around is called longshore drift, which is generated by waves that approach the beach at an angle and drive longshore current development.

How can we use Bowen's reaction series to predict when different minerals will weather?

The minerals at the top that form at high temperature and high pressures will weather first because they are less stable., and when they reach the surface they are trying to react and change to something more stable (i.e. Olivine, Pyroxene, Amphibole, Biotite).

What does the principle of uniformatism state?

The present is the key to the past, rocks can are environmental fingerprints because they can tell us about the environment they came from just like the rock record can help us infer history or the past.

Porosity

The space within rocks and bodies of sediment . Clay particles have high porosity, particles that don't fit tightly. Crystals in granite fit tightly and have low porosity.

What is stratigraphy?

The study of how rock layers (strata) are related to each other.

mechanical weathering

The type of weathering in which rock is physically broken into smaller pieces

The zone of aeration

The upper zone which usually isn't completely filled with water, but with rocks and soil too. It lies above the water table.

How do streams interact with water tables in deserts?

The water table is usually very deep, and most streams are losing streams, between infiltration, and evaporation streams are rapidly depleted.

What type of environment do limestones form in?

These are warm-water rocks that are often associated with coral reefs -in the Bahamas and Southern Florida

How do continental interior deserts form?

These form inland on large land masses, as wind moves inland, it loses moisture through precipitation. no precipitation left to reach the interior of these continents.

Where do braided streams form and what are their characteristics?

They have extremely heavy sediment loads, and frequently variable water levels. This prevents the establishment of plants on banks, which would otherwise help stabilize these systems. We find these in steep, mountainous areas and associated with glaciers.

Why do joints increase weathering rates?

They increase surface area

What characteristics make a good aquifer.

They must be porus and permeable and contain water. Confined (sandwiched between two aquicludes) aquifers tend to have higher water quality , since there are fewer places for contaminants to enter. Unconfined aquifers (open to incoming ground water from the top) are more susceptible to pollution.

What do tides result from (what two bodies exert gravitational pulls on the Earth and its water, and which is stronger)

Tides result from the interaction of the moon and the sun, which exert gravitational pulls on the Earth and its water (the moon exerts about twice the pull that the sun does). Because of this gravitational force, both the Earth and the oceans are pulled towards the moon, creating a bulge of water and earth on the side of the Earth facing the moon. On the side of the Earth directly opposite from the moon, the movement of the Earth towards the moon and also reduced gravitational attraction of the ocean water creates another bulge. The sun has a similar but smaller effect. As the Earth rotates, it moves underneath these bulges-this is what gives us our tides!

What might you observe on a slope that would tell you that creep is occurring?

Tilted fences, breaks in retaining walls, and cracks in roads.

Avalanche (unconsolidated)

VERY FAST motion. Example: in a snow avalanche, air-snow mixture is denser than air and runs along the ground. This moves like a strong and viscous wind. A debris avalanche is defined as a VERY FAST flow of water-saturated rock, dirt, vegetation, and sometimes ice. Speed results from high air or water contents and steep slopes, carries with it everything in its path.

How do water waves move water?

Water particles move in circular orbits. These waves don't move anything anywhere, water depth has to be more than half of the wave length.

Why does substance occur when ground water is over drawn?

Water pushes things apart when we remove water from a pore space, and makes the space bigger, if you take it out you can lose a lot of volume.

Precipitation

Water, such as rain, snow, sleet, hail and unappealing combinations of the above that falls to the ground, from the atmosphere to the hydrosphere.

What is a rouge wave and how do they form?

Waves twice as large as other waves that also frequently come from unexpected directions. Rogue waves are also unusually steep. To build these waves, energy is likely focused by eddies and currents interacting with wave fields. These waves can sink ships, they are often formed from constructive interference.

How have we estimated the age of the Earth?

We determined the age of meteorites which are about 4.55 billion years old. We have dated rocks which were dated 4.46 Ba. We have dated the Earth's oldest rocks which are, 3.9-4Ba and some grains date back to 4.4Ba.

What is desertification? how are we causing it?

When fertile land becomes desert. In many regions of the world, we are having problems advancing deserts, this can be driven by climate change, overgrazing and also drought.

How do midlatitude deserts form?

a result of rain shadows created by mountains.

ventifact

a stone shaped by the erosive action of windblown sand.

desert pavement

a surface or coarse cobbles and pebbles.

Bajada

alluvial fans coalesce to form these, they are an apron of sediment along a mountain front.

Specific Retention

amount of ground water that is retained within source total amount of sediment/rock

Trace fossils

any kind of trace that the organism leaves, on sediments or other organisms.

how do neap tides form?

are boring, average tides that occur when the moon and sun form a right angle with the Earth at the bend. In this situation, their pulls cancel out each other's effects

How do spring tides form?

are exceptionally high tides and exceptionally low tides that occur when the moon and sun are operating in a line.

What is an isotope?

atoms with the same number of protons but different number of neutrons

Why do minerals experience chemical weathering?

change in chemical structure or properties, rocks formed at depth are less stable at surface pressures and temperatures, and will react to produce more stable forms.

Two major classes of sedimentary rocks

clastic and chemical

Leeward side of the mountain.

cold dry air descends, this forms desserts.

Can consolidated or unconsolidated material hold a steeper slope?

consolidated

Shore Face

constantly disturbed by wave action, where waves break.

Flows (unconsolidated)

continuous downslope movement of water-saturated material (rock and/or regolith) that moves like a viscous fluid. The type of flow is classified based on the velocity at which this occurs.

Where does most water use go generally?

cooling stations at different kinds of power plants, and irrigation.

By what chemical weathering mechanism and in what rock type is karst topography formed?

dissolution, sedimentary rock (limestone)

Debris Flows (unconsolidated)

faster than earth flows, and they have bigger chuncks of rocks, they can get up to 60 m/hr in speed. we observe the moderate to rapid movement of water-saturated, primarily coarse-grained unconsolidated materials downslope. These events occur most commonly in semi-arid mountainous regions, and are frequently confined to existing stream channels or canyons. They are often triggered by periods of heavy rains. Lahars are a special kind of debris flow that occurs on volcanic slopes.

Alluvial fan

form at the mouths of canyons and playa lakes and form in the flat central area of undrained desert basins.

Chemical Rocks

form from evaporation, precipitation, or biological processes.

How Karst topography and caves form

formed by the interaction of groundwater with limestone resulting in dissolution.

What is coal made of? How much peat does it take to make 10 meters of coal?

formed from the compression of plant material, like peat, and then you heat it up a little bit. The ratio of peat to coal is __10:1____, so if you compress 30 meters of peat you only get 3 meters of coal!

What drives mass wasting events, in one word?

gravity

Each stratum is laterally continuous

if you dump sediment into a basin under the influence of gravity, it will spread out intill it fills the basin or runs out. because of this sedimentary beds are often laterally continuous for 10s of kms. if rocks look similar even though there is a valley seperating them they are probably the same rocks that formed at the same time, and represent the same enviornment, seperated by erosion.

What makes a good aquiclude?

impermeable layers that restrict the movement of water.

biogenic limestones

includes the skeletons of organisms who pulled material out of solution when they were growing. Most limestones represent the build up of millions of years of shells of different animals.

Faunal Succession

individual species appear and then go extinct, and do not come back. So we can sort out the orders of appearance of different species and use this knowledge to link even widely separated outcrops of each-other, as long as they share the same fossil content.

for what igneous rocks will superposition not apply

intrusive igneous rocks

What is a Lagerstatten deposit?

is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues.

storm weather wave base

is the area on the bottom of the ocean that is only stirred up during storm events when longer wavelength waves impact an area.

Inselberg

isolated mountain remenants caused by eroded mountains.

Playa

lakes

Clastic Rocks

made of stuff that gets broken off of other rocks and has stuck together at surface pressures and temperatures

What happend in Chelyabinsk, Russia on February 15th 2013?

meteor was a small asteroid — about the size of a six-story building — that broke up over the city of Chelyabinsk, Russia, on Feb. 15, 2013. The blast was stronger than a nuclear explosion, triggering detections from monitoring stations as far away as Antarctica.J

Dissolution

minerals are dissolved in fluid and can be transported as ions. (chemical)

What percentage of species that ever lived are extinct?

more than 99%

Salt water intrusion

near the coast, over-pumping of groundwater causes saltwater to move into the aquifer

Nonconformity

not the right kinds how did those igneous or metamorphic rocks get here?

Cones of Depression

occur when pumping locally lowers the water table, can cause shallow wells within the cone of depression that go dry.

Over-budgeting

occurs when discharge is greater than recharge.

Solufluction (unconsolidated)

occurs when only the upper most layer of permafrost melts in high elevation regions in the summer. Ground flows downhill in overlapping sheets, supported by a soggy base that rests on top of unthawed solid ground a few meters down. In the winter everything is frozen, in the summer the whole top layer of the slope thaws out and starts to flow/ move down hill. These are very slow processes.

How does the concentration of organic matter vs. parent material change as we move downwards through soil, into the Earth?

organic matter is situated at the top, and the further down you go the more parent material you will find.

Dissolution and Replacement

original material dissolves and leaves a void we may get infilling with new material

Unaltered Remains

original material is preserved. Commonly occurs in amber, shells made out of aragonite and calcite, in tar pits, and in permafrost where soft tissue and hair may be preserved.

Recrystallization

originally unstable material changes to a more stable arrangement, the overall chemical composition does not change. Aragonite frequently changes to calcite.

Why do Isotopes decay?

parent isotopes have unstable nuclei this makes them radioactive. Unstable isotopes change spontaneously to become another isotope of the same element, or a different element. They lose energy in the process and become more stable.

What is a hydrograph, and how would it differ for a rural vs. an urban area (and why would it differ)?

plot the flow of a stream vs. time. We see a lag in timing of maximum flow as water that has infiltrated into the ground and water that is running as sheet flow over the ground surface makes its way into a stream and down through a drainage basin. Only 1-5% of rain falls directly into a stream during a precipitation event-the rest of the rain will slowly find its way there. Urban areas receive more run-off from rural areas and therefore would have a higher stream v. time.

Permineralization

pores and canals get filled in with minerals, original material may remain (usually in bones and plant material).

Non-biogenic Limestone

precipitates out of solution without the help of living things

Where does most domestic water use go?

public supply

Do Steno's principles and laws allow us to do relative or absolute dating?

relative dating

Transpiration

release of water vapor to the atmosphere by plants through pores in their leaves. (water goes directly from plants into atmosphere, after being absorbed from ground through plant roots)

Zones of discharge

released to the surface at springs, wetlands, streams, rivers, and lakes.

Rock Falls (consolidated)

rock material falls freely and quickly, losing contact with the ground surface. These can be very destructive

facies

rocks and structures indicative of a particular environment.

thermal expansion and contraction

rocks expand when warm and shrink when cool, and they can explode (mechanical)

mineral wedging

salt wedging is especially common, and occurs where evaporation of water leads to the growth of crystals in cracks (mechanical)

Suspended Load (transport)

sediment is suspended in the water (turbulent flow is good at keeping particles suspended). This will support medium to small clasts.

Steppe

semi-arid marginal zone that borders deserts.

Rock Slides (consolidated)

slow to rapid movement downslope of relatively intact rock layers that have detached from a sloped outcrop, and that move along a well-defined rupture surface. Rocks do not fall freely but slide down slope, maintaining contact with it. Layers move downhill as a unit, sliding on underlying surface (usually bedding planes or jointing fractures). Fast Movement, but slower than rockfalls.

Dissolved Load (transport)

soluble ions that have entered the fluid through dissolution are carried along in the water.

superposition (steno's principles and laws)

stacking of strata takes place according to age. the oldest sediment/ rock should be on the bottom and the youngest sediment/ rock should be on top.

How do subtropical form.

subtropical deserts and steppes form due to winds, wind patterns are the deciding factor. We get most incoming solar insolation (heat) at the equator, which causes heated air to rise. As it rises it condenses and precipitation occurs. This now dry air travels about 20-30 N or S high above the earths surface, and then descends as cold dry air. It heats as it approaches the earth's surface and since it is so dry it gives us our desert climate.

Infiltration

surface water drains into the ground through cracks and pore spaces in regolith.

specific yield

the amount of water that will drain out of saturated soil and rock by gravity flow

Fairweather wave base

the area on the bottom of the ocean that is disturbed daily by shallow water waves, given average wave conditions in an area.

What does this have to do with the Corvette Museum and caves?

the cave kept getting bigger under this museum, and eventually the surface caved in creating a pothole, and the corvettes fell in.

What is mass wasting?

the downslope movement of rock, regolith, and soil under the direct influence of gravity

Wave Length

the horizontal distance from one wave crest th the next wave crest

The Eons

the largest division of geologic time. 1. Precambrian Era - before hard shelled life This encompases in order the from oldest to youngest (Hadean, Archean, proterozoic eons)-all rocks older than the camberian are precamberian in age. 2. Camberian Eon (Phanerozoic (todays eon).

Water Table

the level below which pore space is 100% saturated

Body Fossils

the organism itself or parts of its skeletal material, hair, gut, contents, etc...

Clast

the pieces of other rocks that have been eroded.

wave period

the time it takes between the passage of two successive crests.

Wave Height

the vertical distance from the crest of a wave to the trough

What does it mean for a stream network to have a dendritic shape?

they have a branching pattern of tributaries joining together that looks like trees.

Carbonization

thin films of carbon are left behind after decay volatiles. Common in shales and fine grained limestones., observed in plants, fish, vertebrates, and some microfossils.

Dissolution (weathering)

this is a chemical weathering process wherein soluble material dissolves into the stream and is carried away.

Oxidation

this is a common weathering mechanism in mafic rocks, which contain Fe-rich minerals. When you see red rocks, you know that they usually experienced weathering in a terrestrial (on land) environment with abundant oxygen. ***Things with Iron will oxidize (chemical)

limestone

this is a very calcite-rich rock. Grains in limestones are often made by animals, and they often act like clastic grains. Limestone can be biogenic or non-biogenic-in Iowa, if you see it it was made by animals most of the time.

bed load (transport)

this is transport for larger clasts (cobbles and boulders). Sediment bounces and rolls across the stream bed.

What can we learn about studying lithified dune deposits and their crossbeds.

to infer past wind conditions, as well paleoclimate ( id we find dunes, we know it was arid).

Root Wedging

trees grow relatively quickly in comparison to the span of geologic time, and their roots can pry rocks apart. (mechanical)

Turbulent flow (weathering)

turbulent flow can loosen and lift material from the stream bed by using water pressure.

Zones of Recharge

water added by infiltration and rainfall possibly from streams and lakes.

Water

water causes weathering largely by abrading rocks with the rocks that it is transporting. (mechanical)

Runoff

water flows over land, rather than infiltrating into the ground.

Hydrolysis

water reacts with carbon dioxide to produce carbonic acid, which weathers silicate rocks into clays, bicarbonates, and other ions. ***This is a common way by which the mineral feldspar weathers. (chemical)

Evaporation

water turns from liquid into a vapor, and moves into the atmosphere.

abrasion (weathering)

water-borne particles physically smash into each-other, and break off pieces of each-other.

What is a desert?

we define these dry climate zones as areas where yearly precipitation is nor as great as the loss of water by evaporation. A desert is extremely arid, driest of dry climate zones.

Earth Flows (unconsolidated)

we observe the moderate to rapid movement of water-saturated, fine grained sediment downslope, commonly on hillsides in humid areas during heavy precipitation or snowmelt.

How does weathering differ from erosion?

weathering is the breakdown of rocks at the Earth's surface, Erosion is the transport of Earth materials from one place to another via gravity, flowing water, wind and glaciers.

Unloading

when rocks form at depth, uplift and erosion may expose them and cause them to form an exfoliation dome, where they flake off in sheets. Rocks form at depth, under high confining pressures, and then when exposed at the surface, they crack apart.. (mechanical)

for what igneous rocks will original horizontality not apply?

when there are no xenoliths

1. How do waves change as they move into shallow water (what happens to their orbits)?

when waves reach a water depth that is half their wavelength or less, they start to "feel" the bottom: orbits become elliptical and the wave is frictionally slowed and leans forward, getting taller. At 1/20th wavelength, the waves break.

The Capillary Fringe

where water rises into the pore space above the water table due to capillary action.

Characteristics of a good index fossil

widespread; rapidly evolving; easily recognizable. The conodont animal is an index fossil used to subdivide time in the Ordovician-Devonian.

Disconformity

wrong ages ( we skip parts of the geologic time scale due to either a lack of deposition and then removal of material through erosion or we are missing time and our record is discontinuous.

angular unconformity

wrong angles, there are nice and obvious.

cross-cutting relationships

younger features cut across older features this includes faults, erosional surfaces, dikes, veins etc..

How are floods defined?

your river leaves its channel. Levees often help contain the channel and can be natural or artificial. Once the channel is breached, the stream spreads out across its floodplain and deposits fine sediment on the floodplain after dumping coarse sediment next to the stream channel (levees are built of this coarse sediment).

The zone of saturation

zone where all open spaces in sediment and rock are completely filled with water, the area of 100% saturation