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127 Cards in this Set
- Front
- Back
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What is Diastrophism
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deformation of earth’s crust
Deformation without movement |
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Diastrophism
Deformation without movement |
Jointing: fracture of rock without displacement
Affects resistance of rock to erosion (weakens) |
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Diastrophism
Deformation with movement Folding:... Faulting:.... |
Folding: bending rock without breakage
Faulting: fracture of rock with displacement (either vertical or horizontal movement) |
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Diastrophism:
3 Types of Stress |
Compressional
Tensional Shearing |
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Diastrophism:
Compressional |
Rocks move together (convergent motion)
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Diastrophism
Tensional |
Opposite movement (divergent motion)
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Diastrophism:
Shearing |
Tearing (transform motion)
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Diastrophism:
Causes of stress |
Confining pressure
Temperature Extreme heat folds the rock without breakage Extreme cold fractures the rock Strength/Composition of rock Time |
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Diastrophism:5 types of folds
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Monocline
Anticline Syncline Overturned Overthrust |
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Monocline
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one-sided slope. Slight bend in otherwise parallel layers of rock
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Anticline
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simple symmetrical upfold, resembles an arch. Due to compression.
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Syncline:
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rock is warped downward –due to compression.
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Overturned
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upfold that has been pushed so vigorously from one side that it becomes over-steepened.
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Overthrust
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pressure was great enough to break the over-steepened area and cause a shear (a break).
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Types of faults
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Normal: One block is displaced up, the other down. Due to tension.
Reverse: A block is pushed up and over the other. Due to compression. Strike-slip: Adjacent blocks are displaced laterally. Movement is entirely horizontal.Due to shearing. |
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Graben
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Subsidence of one middle block (it drops down). Due to tension.
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Horst
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2 reverse faults push a middle block up. Due to compression
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focus
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point of origin
energy is transmitted to surrounding rock by waves |
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Epicenter
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Surface location of focus (directly above the origin).
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rock moving due to folding or faulting results in.....
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Sudden vibration within lithosphere from a quick release of energy
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Types of Energy Waves
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Body Waves
Surface Waves |
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Body Waves
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Occur first. These are the initial waves emitted from the earthquake. These occur in a specific order.
1stwave: Primary “P”wave. 2ndwave: Secondary “S”wave. |
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Surface Waves
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Occur after the body waves. These affect the surface of the earth (we typically feel these)
Type 1: Love wave. Type 2: Rayleigh wave |
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Primary Wave (P wave)
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Expansion & contraction of rock
as wave moves through it Fastest body wave Moves through solid rock and fluids (e.g., ocean/water) |
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Secondary Wave (S wave)
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Wave moves through rock up and
down and side-to-side Slower than P wave Can only move through solid rock |
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Love Wave
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Rolling/swaying effect on surface
Moves the ground from side-to-side Fastest surface wave |
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Rayleigh Wave
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Rolls along ground like an ocean wave
Type most often felt during quakes |
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Methods of measuring earthquakes
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Modified Mercalli Intensity Scale
Richter Scale |
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Modified Mercalli Intensity Scale
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Measures “intensity”of earthquake (e.g., the amount of shaking felt and the damage done).
Very subjective: depends on the viewer’s description of the earthquake event! Based on observations. |
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Richter Scale
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Measures the “magnitude”of earthquake (the energy waves released).
Based on readings from a seismograph, and examining the actual energy waves. |
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Logarithmic Scale
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Each increase in magnitude is 10x more energy released
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Determining the magnitude of an earthquake
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A seismologist reviews data taken by a seismograph.
View the following: seismograph animation Two important pieces of data to record: Lag Time: difference in time between the P wave and the S wave (when each is picked up by the seismograph). Designated as “S –P” Given in seconds. Amplitude: the size of the largest S wave (the height of the wave). Given in millimeters. |
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Lag Time
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difference in time between the P wave and the S wave (when each is picked up by the seismograph)
Designated as “S –P” Given in seconds. |
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Amplitude:
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the size of the largest S wave (the height of the wave).
Given in millimeters. |
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Fluvial
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stream-related processes
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Geomorphology
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analysis of how landforms evolve
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Fluvial Geomorphology is ..............
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important in understanding how water shapes our earth
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Types of work performed by streams
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3 types of work
Erosionof landscape Streams carry mixture of water and solids Alluvium= clay, silt, and sand that is transported & deposited by running water Transportation of materials Depositionof materials Concept of “Base Level” Lowest (elevation) point to which a stream can flow and cut down to Ultimate base level = sea level |
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watersheds and drainage basins
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Streams organized into areas
All the water in the area flows into one stream and exits in one spot. Can be broken down into sub-basins(see map of Georgia). |
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drainage divides
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High ground which separates streams that are flowing
in adjacent basins. Streams cannot cross the divide. |
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7 common patterns of streams
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Dendritic
Rectangular Trellis Radial Parallel Deranged or Chaotic Centripetal |
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Classify patterns of streams in a basin
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“First-order” streams are smallest
Any basin will have more first-order streams than any other category. Think of these as headwater streams. Where 2 similar-ordered streams come together, they increase in order 2 streams of same order must be joined to increase in order. Otherwise, keep the higher number for the next stream. |
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Categories of Streams
Straight Channel |
Uncommon, usually only occurs in canyons or when humans force rivers to straighten out
Examples: portions of the Columbia River (states of Washington and Oregon) and the Colorado River (southwest U.S.) |
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Categories of Streams
Braided Stream |
Forms when the stream cannot hold its sediment load and dumps it in the middle of the channel.
Channel bar sare collected piles of sediment Channel bars force the river to flow around them, which separates the river into “braids” Platte River |
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Categories of Streams
Meandering Stream |
Sinuous channel
Form through deposition and lateral erosion Deposition= inside bank (slower velocity water allows alluvium to collect here) Erosion= outside bank of the meander (higher velocity water erodes the bank) |
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Cut Bank
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Erosion taking place on the outside of
the meander |
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Velocity
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how quickly water is moving through the stream
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Discharge
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volume of water transported by a stream
The greater the discharge, the more ability it has to carry sediment In times of flooding, discharge is higher than during periods of infrequent/low precipitation. Need to know velocity & area of the stream’s channel. |
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Area (A) =
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Width (w) x Depth (d)
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Discharge (Q) =
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Velocity (v) x Area (A)
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Floodplains
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form when the river leaves its channel during times of high flow.
Natural levees are produced from flooding Yazoo streams may form on the other side of levees –cannot join the main channel because of the levee. |
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Recurrence
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average time period when an event will be equaled or exceeded
Likelihood of occurrence each year Used to designate different flood zones |
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calculating Flood recurrence
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(1 ÷Frequency) x 100
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Midwest Floods of 1993
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Most devastating flood in recent US history
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Karst
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a landscape formed mainly by rock being dissolved by surface or groundwater.
2 key ingredients: Rock (typically limestone) + Water mostly occurs in humid regions where carbonate rock (e.g., limestone) is present |
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Limestone
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Sedimentary rock
Calcium Carbonate: CaCo3 Extremely soluble in water Rectangular jointing: fractures in the rock which allow water to easily travel through limestone |
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Dissolution
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process of rock dissolving when it comes into contact with water
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Karst Formations
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Sinkholes (also called a “doline”)
Surface water features Disappearing Streams Springs Karst Towers Caves |
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Sinkholes: 3 types
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Solution Sinkhole
Cover-Subsidence Sinkhole Cover-Collapse Sinkhole |
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Solution Sinkhole
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Little or no sediment is present over limestone
Easily dissolved by water |
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Cover-Subsidence Sinkhole
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Thick sediments overlay limestone
Underlying limestone is dissolved, sediments dump into the void |
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Cover-Collapse Sinkhole
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Triggered by heavy rainfall, drought, overloading
Cause sudden collapse into void |
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Surface Water Features
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Karst regions are noted for their lack of well-established surface drainage.
Surface drainage is actually replaced by extensive underground drainage. Where surface streams do develop, they do not flow very far –they “disappear”(disappearing streams)and “reappear”(springs). |
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Towers
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Formation is due to a
combination of tectonic uplift and tropical erosion. |
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Caves
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Forms in a manner similar to sinkholes
Water travels through (limestone’s) rectangular joints and dissolves limestone, leaving a void below ground Often have other limestone formations within the cave |
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Caves: common interior formations
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Soda Straws
Stalactites & Stalagmites Columns(stalactites & stalagmites grown together) Pool spar & shelf stones |
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Pool Spar
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crystallization of dissolved limestone
in water |
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shelfstone
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when spar attach to side of a cave pool
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Columns
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when stalactites &
stalagmites grow together |
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Aquifer
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an underground layer of permeable rock containing water. Sometimes, the aquifer is “confined” between two layers of impermeable rock.
Unconfined aquifers allow water to easily pass in and out (from above and below) |
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Water Table
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the level at which underground water stays. It is the very top of the zone of saturation.
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Ogallala Aquifer
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174,000 sq. mi
Depths up to 500+ ft Much of water dates back to last ice age! depleting |
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Floridan Aquifer
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100,000 sq. mi
Serves multiple urban areas Agricultural purposes Water |
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Principal Forces for Erosion
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1. Tides
2. Sea-level changes 3. Waves 4. Currents 5. Stream Outflows |
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Tides
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Oscillations of ocean water: gravitational pull of the Moonand Sun
24 hours: High-Low-High-Low tide periods2 |
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Sea-level changes
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Rising/Falling results from tectonic activity or amount of waterin ocean
Creates emergence (above water) and submergence(below water) coastlines |
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Waves
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Most important erosional force
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Currents
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Large volumes of water moving horizontally
Consistent winds create currents “Longshore” currents transport sediment down a coastline (helps in formation of beaches) |
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Stream Outflows
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Spills sediments out into the ocean and adds material to beaches
Deltas often form at the mouth of rivers –why? |
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Barrier Island
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Long, narrow, low island that lies parallel to a shoreline.
Buffers the mainland from storms and large waves. |
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Lagoon
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Nearly isolated body of water, separated from sea by the barrier island.
•Low-energy waves and relatively calm area, so sediments may accumulate. •Mudflats, marshes, swamps |
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Barrier Spit
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Coastal barriers that
extend into open water, attached to the mainland at one end. Can develop into a barrier island if it becomes separated from the mainland. |
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Beaches
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eroded continental material (sand, gravel, rock fragments) that are washed to the sea by streams.
Sediment gets suspended in sea water and is often transported further down the coastline by longshorecurrents Long shore currents provide a continual onshore-offshore movement which pushes the sand along the beach edge. Often called “littoral drift.” |
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Fringing Reef•
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Forms along shoreline of volcanic island (hot spot) –it likes the warm waters!
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Barrier Reef
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Island begins to sink or erode, but reef continues to grow upward. Lagoon is created between the top of the reef and the sinking island.
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Atoll
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Island sinks/erodes below sea level, reef continue to grow upward.•If a “broken circle” of reef, it is likely due to storm action.
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Tombolo
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A narrow piece of land between the shore and an island, or between two islands
.•Forms because wave refraction around islands causes sand and sediment to build up in a linear formation where the waves meet (around the backside of the island) |
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Wave-cut Arches
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Formed by wave action which erodes less-resistant rock from an outcrop.
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Wave-cut Platforms
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Formed after waves hit against a cliff face, causing undercutting.
•Most obvious at low tide when they become visible as huge areasof flat rock . •An “extreme” environment (for marine life) because of continualwave action. |
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4 Typical Conditions
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Sparse cover of vegetation and soil
Impermeable surface layers Rain is infrequent, but short-lived & intense Interior drainage = centripetal Ephemeral streams flow to the bottom of basin Alluvium is deposited and water evaporates, sometimes leaving behind a salt layer |
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Principal Forces for Erosion
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1. Water
2. Wind |
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Alluvial Fan
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When streams come out of steep canyons…
the velocity of the stream drops dramatically, and… the slope of the river decreases. Therefore, alluvium is deposited! Edges of the fans may be clearly defined. Bajadas are formed when multiple alluvial fans join along a mountain front |
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Bajadas
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formed when multiple alluvial fans join
along a mountain front |
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Inselberg
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Isolated hill/ridge, steep-sided
Formed when less-resistant material is eroded away from more-resistant rock (often an intrusive formation). Example: Uluru(Ayers Rock), AU |
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Playa
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Dry lake bed
Found at lowest point of basin Recognizable by dried mud, often covered w/ crust of salt |
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Pinnacles
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Isolated hill with steep sides and pointed or flat top
“Caprock” (resistant) remains while softer rock is eroded away Typical of southwest U.S. |
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Buttes
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Larger than a pinnacle, flat top
Example: Chimney Rock, NE |
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Mesas
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Larger than a butte, smaller than a
plateau. Flat top. |
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Sand Dunes 4 main shapes
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Barchan
Transverse Longitudinal Blowout |
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Barchan
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Limited supply of loose sand
Crescent-shaped “Horn” points downwind Wind blows constantly in a single direction Migrates downwind over long time |
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Transverse
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Less uniform than Barchan
More supply of loose sand Maintains general crescent shape Usually forms interconnected ridges of sand |
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Longitudinal
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a.k.a. “Seif”
Wind directions shifts back & forth Long parallel ridges Egypt |
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Blowout
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Wind erosion
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ADVANCING
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(cold temps + moisture = accumulation)
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RETREATING
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warm temps = melting)
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Zone of Accumulation
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Area where glacier is gaining precipitation
Upslope –higher elevations |
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Zone of Ablation
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Area where glacier is melting
Downslope–lower elevations sublimation occurs when ice is directly changed into water vapor (skips the steps of the ice actually melting and changing to water, then evaporating) |
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Sublimation
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occurs when ice is directly changed into water vapor (skips the steps of the ice actually melting and changing to water, then evaporating)
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Last Ice Age: Where were they located?
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2 MYA (Pleistocene), max extent: 1/3 land covered
Now: 10% land covered 96% glacial ice is tied up in Antarctica & GreenlandxKCxOmahaSt |
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Glacial Processes
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Erosion
Transportation & Deposition Glaciofluvial |
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“Plucking”
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Water gets in cracks, freezes, lifts up bits of rock and carries them in the glacier itself
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Scouring
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Abrasive action of rocks within glacier as glacier moves over surface
Leaves striatedsurface Enough scouring creates a polished surface |
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Transportation & Deposition
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Debris within glacier = transported
Debris ahead or to sides of glacier = deposited |
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Moraines
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till gets pushed into linear piles by the movement of a glacier.
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All formed by deposition of materials…
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Moraines
Kames Kettles/Kettle Ponds Braided Outwash Streams |
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Terminal Moraine
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marks the maximum extent of the glacier
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Recessional Moraine
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develops behind theterminal moraine as the glacier retreats
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Kames
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Steep-sided, conical hill of debris that originally collected in a hole in the glacier.
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Kettles
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Large chunks of ice leave a depression in the landscape because…
Isolated ice issurrounded by till(which becomespart of thelandscape).Ice melts –leavinga “depression”. If filled with water,called “kettle lakes” |
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Alpine Glaciers Features due to Erosion
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Cirque
Tarn Horn Arete Glacial Valley Hanging Valley Paternoster Lakes |
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Cirques
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Bowl-shaped depression (think: amphitheatre)
Area where snow first accumulates and modifies into glacial ice |
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Tarns
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After a glacier is no longer present, a lake may form in a cirque
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Horns
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Pyramidal peak that forms when cirques chisel a mountain from 3+ sides
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Aretes
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Narrow ridge formed when two glaciers move down valleys and erode the area between them into a ridge
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Glacial Valley
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Valleys become deeper & wider over time
Guide the path of glacial ice flow U-Shaped |
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Hanging Valley
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When smaller valleys join with larger glacial valleys, the floors are not at the same elevation
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Paternoster Lakes
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Chain of tarns that are formed when a valley “steps” down
Lakes are all connected by streams and/or waterfalls |
