Geo Exam One

Front 1

Floating of lighter on heavier layer in equilibrium.

Back 1

Isostasy

Front 2

Types of Earth's materials

Back 2

Brittle (break) - high stress applied fast
Elastic ("bounce") - low-medium stress applied fast
Plastic (flow) - low-medium stress applied slowly

Front 3

Areas of thick, deformed, sedimentary rocks, usually in mountains.

Back 3

Geosynclines

Front 4

Features of Geosynclines

Back 4

- v. thick sediments (2,000 ~ 16,000 m)
- moderate-to-severe folding (a compression gf)
- thrust faults (a compression gf)
- mountain-building (deep roots, high surface)
- (regional) metamorphism
- granitic intrusions (batholiths)
- clastic wedges (as mtns. erode)

Front 5

part of geosyncline near continent

Back 5

Miogeosyncline

Front 6

part of geosyncline near ocean

Back 6

Eugeosyncline

Front 7

the history of a geosyncline

Back 7

Depostional part-->Terminal Orogeny--->Erosional part

Front 8

name the three different plate boundries

Back 8

continent-continent
ocean-continent
ocean-ocean

Front 9

spreading mechanisms for spreading

Back 9

"push", "pull", gravity sliding, convection currents
shallow vs. deep convection

Front 10

evidence for mobile continents

Back 10

1. fitting and mathching of continetns margins, surface geology
2.climatically controlled features, glacial deposits, glossopteris, plants, messosaurus, lystrosaurus (terr. "theapsid reptile")
3. Paleomagnetism-pole postions through time magnetic reversaks
4.ocean features-magnetic anomalies
5. seismic information-earth quake zones, heat flow from crust, asthenosphere (low-velocity zone) hot spots, plates, active boundries

Front 11

Most common feature (~90%) found in sediments

Back 11

Bedding

Front 12

a single episode of deposition, one type of sediment, usually 1mm-2m
~90% of sedimentary thickness, 1-50% of time

Back 12

Bed

Front 13

small breaks between beds
~10% of thickness, 50-99% of time

Back 13

Bedding-planes

Front 14

Unusual types of beds (not horizontal, unusual shape, or additional features)
- other 10% of features found in sediments

Back 14

Sedimentary Structures

Front 15

Sedimentary structures tells us

Back 15

up" direction and/or current direction
- depositional agent
- depositional environment

Front 16

Name the types of sedimentary structures

Back 16

cross bedding (sand wave, dunes) - 3%
ripples (current, oscillation) - 2%
graded bedding - 1%
flute casts - 1/2%
mud cracks, raindrop impression - 1%
channels - 1%
flat-pebble conglomerates - 1/2%
concretions (diagenetic feature) - 1/2%
several others

Front 17

name the sed rocks and percentage of each

Back 17

Evaporties-23%
limestones-14%
Shales-63%
Sandstones-21%

Front 18

why are shale and sandstones the most abundant

Back 18

-sediments are differential units of grain size.
-most soil made of clay(shale). contains organic material for plants to grow
-shale mostly comes from weathering silicates
-also carbonates break down and form into shale
-difficult to get rid of silicate very stable

Front 19

name the deacreasing size of sediment

Back 19

boulders-->pebbles-->sand------->silt-->clay--->limestone-->shale

Front 20

Continental Shelf

Back 20

- a continental shelf is the edge of a continent where it slopes down steeply to the bottom of the ocean.

Front 21

Continental Slope

Back 21

the seaward border of the continental shelf.

Front 22

Oceanic subdivisions

Back 22

abyssal plains (deep sea), mid-ocean ridges (underwater mountain system that is known as having the characteristic of oceanic spreading center, which is responsible for seafloor spreading), trenches (convergent boundary where subduction is occurring)

Front 23

Terminal Orogeny

Back 23

- end of geosyncline, no more sediments, no more formation. Two large continents running into each other. Laurentia/Gondwana. Lots of deformation, big mountains, erode slowly.

Front 24

Plate boundaries

Back 24

○ Mid-ocean ridge (spreading centers)
○ Trench (subduction zone) where plumes reside
○ Transform fault (fracture zone, sliding motion)
○ Divergence (pull apart)
○ Convergence
■ area between 2 continents will be a mountain range and will take out a quarter of the living area
■ mountain organisms move in (small immigrants have a little impact, but large immigrants could cause extinction in smaller immigrants)
○ Sliding
○ Currents carrying lithosphere

Front 25

Asthenosphere (low-velocity zone)

Back 25

below the lithosphere in upper mantle (200-300 km deep). Another boundary where lateral motion goes on at top of convection current. Currents carry lithosphere.

Front 26

Active Margin

Back 26

a boundary (transform, convergent, divergent) with plate activity, such as: earthquakes, volcanoes, mountain building, rifting, trenches, etc.

Front 27

Passive Margin

Back 27

- a boundary with no plate activity

Front 28

Hot Spot

Back 28

active volcanism not near plate boundary, many in oceans, few in continents. Iceland along ridge, big island because hasn’t moved, on stable ridge, big intrusions keep coming up and forming more island, it’s also splitting apart. Other examples: Galapalos, Yellowstone, Hawaii (middle of plate which would otherwise be stable).

Front 29

Plume

Back 29

an upwelling of molten material from the earth’s mantle.

Front 30

Island arc (2 kinds)

Back 30

○ (Exotic) terrain: rocks don’t match, they come in as an island arc (Ex: Rockies)
○ Tectonic tracers: an indication that an area that you’re in doesn’t belong to continent attached to, but a continent of the past (Ex: Appalachians, west Europe)

Front 31

Rift Valley

Back 31

- a linear-shaped lowland between highlands or mountain ranges created by faulting, deepened by erosion

Front 32

Aulacogen

Back 32

failed arm of triple junction of a plate tectonics rift system.

Front 33

Wilson Cycle:

Back 33

opening and closing of ocean (Paleozoic breaking up Rodinia and then coming together to form Pangaea. Plates went apart for awhile and then came back together. Ocean subducts, even on other side of plate boundary. Ocean crust going down a distnace, then area would heat up below.

Front 34

Ophiolites

Back 34

basaltic ocean crust trapped in mountain. This is the only sample of older oceanic crust we have since it subducts underneath continental crust.

Front 35

Pangaea

Back 35

- Across (Pan) the Earth (Gaia). Existed between Paleozoic and Mesozoic. In Jurassic, it began to rift from the Tethys Ocean in the east and the Pacific in the west.

Front 36

Rodinia

Back 36

Proterozoic. Africa broken into four pieces. Europe stuck on South America and Greenland.

Front 37

Gondwana

Back 37

southernmost of two continents (the other being Laurasia) that formed part of the Pangaea supercontinent.

Front 38

Intermediate Orogeny

Back 38

some small crustal fragment runs into continent, or subduction goes on for a long time (ex: continental fragment, island arc).

Front 39

types of sandstones

Back 39

orthoquartzite (~pure quartz) - very stable
- arkose (lots of feldspar)
- greywacke (rock, fragments, etc.)