Term
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Definition
| a big hole fills with sediments and would finall shoot up after pressure was released. Places where mountains are now used to be big holes (geosynclines) |
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Term
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Definition
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Term
| Give 4 reasons/evidence for continental drift theory. |
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Definition
1. Africa's and South America's continental shelves fit well geographically
2.continuation of structural trends between continents now separated by ocean basins
3. identical fossils are found on continents that are no longer near eachother
4.paleoclimactic similarities between continents now fair apart (glacial deposits) |
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Term
| What two technological improvements/more comprehensive data collection led to plate tectonic theory? |
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Definition
1. detailed maps of the sea floor (mid ocean ridges, trenches, fracture zones) result of sonar invention
2. comprehensive sea floor and continental magnetometer surveys. |
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Term
| At what temperature must iron bearing rocks cool below to lock in the ambient magnetic field? |
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Definition
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Term
| What does a magnetometer measure? |
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Definition
| measures strength and polarity of magentic fields. Can find landimines. |
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Term
| What is apparent polar wander and how does it help prove plate tectonics? |
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Definition
| Rocks don't point in the same directions for poles, rocks couldn't have moved. Apparent polar wander is the change in the apparent north pole according to the rocks in various places. shows polar wander and polar wander does not match in rocks until the US and Europe are fit back together. |
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Term
| What did the Ocean Drilling Project conclude about deep ocean floors? |
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Definition
1. 100% basalt
2. age increases w/ distance from mid-ocean ridges
3. sediment thickness increases with distance from ridges
4. age of oldest sediment increases with distance from mid ocean ridges |
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Term
| What do the magnetometer readings of the ocean floor near MOR's show? |
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Definition
| Some show a magnetic field less than the one we experience today while others show a magnetic field greater than the one we experience today. These are formed into bands parallel to MORs. |
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Term
| Who is responsible for the sea floor spreading theory, what exactly did they propose? |
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Definition
| Vine and Matthews. Sea floor is created at MORs and spreads. Hot asthenosphere rises beneath MORs, decompresses while cooling, splits apart and spreads. |
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Term
| What is the oldest oceanic crust? |
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Definition
|
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Term
| What are guyots? Where do they form? |
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Definition
| a fully submerged former island that formed over a hot spot. It rides on the piece of oceanic crust it formed on and it rides that piece of oceanic crust deeper and deeper, as the sea floor slopes away from MORs. Eventually it is submerged and no longer above the hot spot. |
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Term
| What drives plate tectonics? |
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Definition
| convection resulting from a loss of heat from the interior of the earth that originates from radioactive decay |
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Term
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Definition
| the fastest moving tectonic plates are those with trenches |
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Term
| What does the wilson cycle describe? |
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Definition
| Presented by J. Tuzo Wilson, it describes the life cccle of supercontinents and ocean basins. Beginning with one supercontinent 3 prong rift systems break out above hot spots that build up. These begin pumping out basalt pushing the continents apart, resulting in cracks that begin to link up the 3 prong rift systems. Some rifts die and others turn into spreading ridges driving the pieces of the supercontinent apart. They eventually run into eachother again and build up. |
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Term
| Why does the wilson cycle use "3 prong rift systems"? |
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Definition
| Because basalt cools hexagonally |
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Term
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Definition
| Due to isostasy. Elevations on earth are a result of the variation of desity and layer thickness of the lithosphere floating on the asthenosphere. |
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Term
| What is pratt isostasy and what is airy isostasy? |
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Definition
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Term
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Definition
| the downward slope movement of rock due to GRAVITY. GRAVITY IS INVOLVED. ALWAYS. |
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Term
| What is the angle of repose? |
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Definition
| the maximum angle a slope is stable it (where mass wasting will stop occurring). gravity, slope and friction govern it |
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Term
| What are 3 ways to initiate slope failure? |
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Definition
| make the angle steeper, earthquake, add water(heavier and a lubricant) |
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Term
| How is mass wasting classified? |
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Definition
| by type of material and type of motion |
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Term
| What are 4 types of material involved in mass wasting? |
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Definition
|
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Term
| What are 4 types of motion involved in mass wasting? |
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Definition
| slide(moves as a coherent block), avalanche(particles suspended in air behaving like fluid due to great deal of energy), flow(moves as a vicous fluid), fall (free fall) |
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Term
| Is a rock slide possible? |
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Definition
| yes a block of rock can slide down an incline plane (mt. st. helens) |
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Term
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Definition
| Mud cannot move as a "coherent block". it flows. . . |
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Term
| Is a mud avalanche possible? |
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Definition
| No, mud cannot become a free flowing fluid, instead it will always be a viscous fluid. |
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Term
| What type of mass wasting has the lowest rate of motion? |
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Definition
|
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Term
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Definition
| the downward sliding of rock or unconsolidated material along a curved plane of failure |
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Term
| What occurs with permafrost in the summer time? |
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Definition
| The top layer becomes liquidy and warm and slides down the frozen lower layer. |
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Term
| What governs the velocity of streams? |
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Definition
| the gradient(vertical drop over a fixed distance), channel shape/size, the amount of water (discharge) |
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Term
| What is discharge defined by? |
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Definition
|
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Term
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Definition
| the lowest elevation a stream can erode its channel. There are local base levels and ultimate base level (sea level) |
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Term
| What does raising base level for a stream promote? |
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Definition
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Term
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Definition
| A stream has eroded to near its base levl. No erosion and no deposition is occuring in the stream. It becomes a sediment conveyor. |
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Term
| What are the 3 ways a stream erodes? |
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Definition
Abrasion-suspended particles hit sides of channel
Lifting-unconsolidated particles are lifted from the bottom
Solution-dissolves ions into solution |
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Term
| What effects the settling out of carried particles? |
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Definition
chemical composition change may force material out os solution
a lowering of velocity allows particles to settle out according to settling velocity |
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Term
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Definition
| deposition occurring on inside of bends in stream where the current is slower |
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Term
| Give 5 characteristics of youthful streams |
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Definition
actively cutting downward
few meanders
narrow, constricted valley, V-shaped
energy is directed downward
found in mountains and include rapids and waterfalls |
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Term
| Give 3 characteristics of mature streams. |
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Definition
a flood plain has developed
meander belt is same size as flood plain and is actively widening
energy is directed side to side, results in meanders |
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Term
| Give 4 characteristics of old age streams. |
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Definition
nearing base level-->no deposition/erosion
flood plain is several times wider than meander belt
little directional energy
reworks and moves sediments |
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Term
| How can streams be rejuvenated? |
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Definition
by raising ground or lowering base level
---results in down cutting and entrenched meanders |
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Term
| Where do you find braiding streams and what characterizes them? |
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Definition
| They have crisscrossed channels as the sediment supply exceeds carrying capacity of the stream. found near glaciers or in the desert |
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Term
| What is occurring in new orleans that will result in it sinking lower and lower? |
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Definition
| It is cut off from receiving the deposits from flooding and the entire area is sinking into the ocean so it is falling beneath sea level |
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Term
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Definition
| As a stream leaves the mountains it fans out and slows down, deposition sediment in the valley. |
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Term
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Definition
| As a stream enters base level, ex. the ocean, it looses velocity and deposits a great deal of sediment blocking it over and over resulting it fanning out quite a bit. |
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Term
| What is a dentritic network characteristic of? |
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Definition
| unifrom errodability of the bedrock |
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Term
| What is a trellis drainage characteristic of? |
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Definition
|
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Term
| What is rectangular drainage controlled by? |
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Definition
| jointing and water flowing through joints. |
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Term
| What melted resulting in the Missoula Floods? |
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Definition
|
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Term
| What is an antecedent stream? |
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Definition
| A stream that flowed before topography was created. Results in downcutting as the topography goes up and creates a water gap. (wallula gap) |
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Term
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Definition
| A result of an anticline rising faster than a stream could downcut and eventually diverting the stream. |
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Term
| What do you call a stream that has a dentritic drainage network over folded strata? |
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Definition
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Term
| What kind of stream network do folded strata usually encourage? |
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Definition
|
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Term
|
Definition
| a thick ice mass that originates on land from an accumulation, compaction and recrystallization of snow and shows evidence of past or present movement |
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Term
| What happens when snowfall in the winter exceeds summer melting? |
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Definition
|
|
Term
| What is the zone of accumulation on a glacier? |
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Definition
| where the snow falls and is snowy. moves around during the year |
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Term
| Where is the zone of oblation on a glacier? |
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Definition
| where it is melting and the glacier is bare ice |
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Term
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Definition
|
|
Term
| Where does ice form on glaciers? |
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Definition
| In the zone of accumulation |
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|
Term
| What is base level for glaciers? |
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Definition
| Below sea level! Unique to each glacier |
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Term
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Definition
| valleys where a glacier had previously met the ocean and melted in its entirety |
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Term
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Definition
| sterams of ice borderd by moutains |
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Term
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Definition
| flow out in all directs from center of accumulation and bury all but the highest mountains. HUGE |
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Term
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Definition
| floating extension of an ice sheet |
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Term
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Definition
| small scale ice sheets found in high latitude mountains |
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Term
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Definition
| valley glaciers that drain ice caps and sheets |
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Term
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Definition
| tributary valley glaciers that form into one at the foot of mountains |
|
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Term
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Definition
| fundamentally limits mountain heights with its great erosive power |
|
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Term
| what controlls the rate of erosion of a glacier? |
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Definition
thickness of ice
rate of movement
shape, size and abundance of rock fragments
erodability of the substrate |
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Term
| What two mechanisms do glaciers use to erode? |
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Definition
Plucking-incorporation rock into ice via frost wedging
Abrasion- ice with embedded rock grinds over the bedrock creating rock flour |
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Term
| Which type of glacier subdues the landscape? |
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Definition
|
|
Term
| which type of glacier accentuates the landscape? |
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Definition
|
|
Term
|
Definition
| created by the main glacier downcuting faster than tributary glaciers |
|
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Term
|
Definition
| U shaped, broad deep and straight |
|
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Term
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Definition
| cyclopean steps between lakes, lakes like beads on a string that step down a level with each one |
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Term
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Definition
| bowl shpaed valley at the head of a glacier trough |
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Term
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Definition
| back wall of cirque. formed by plucking |
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Term
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Definition
| lake on the floor of a cirque |
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Term
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Definition
| a high ridge separated glaciers |
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Term
|
Definition
| lo spot on an arête, a high pass where 2 cirques meet |
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Term
|
Definition
| an isolated peak produced by the enlargement of cirques |
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Term
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Definition
| (back of a sheep) bedrock outcrops having polished gently-sloping sides that face up the glacier with steep sides facing down |
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Term
| What is the ocean floor made of? |
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Definition
| From top to bottom: pillow basalts, sheet dikes, gabros and below moho ultramafic rocks |
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