Review for test 1 - geology part 2

Which of the three major rock types is most common at the surface of the Earth?

sedimentary

The back and forth movement of waves at the beach produces special sedimentary structures in the sand. These are called:

ripples

How is unconformity created?

rock layers are tilted by tectonic forces

Carlsbad Caverns, New Mexico, and Cathedral Caverns, Alabama, are both formed in the same rock type, limestone. True or false: If the same rock type is found in both places, the rocks have to be the same age.

false

Earth system → rocks, soil, volcanoes, earthquakes

geosphere

Earth system → air, weather, climate

atmosphere

Earth system → oceans, rivers, rainfall, glaciers

hydrosphere

Earth system → animals, plants, microorganisms, fungi

biosphere

The break-down of older rocks into sediment

weathering

When sediment created by weathering starts moving (removed from where it formed)

erosion

When sediment is moved somewhere new (often by water, wind, gravity, or ice)

transport

Sediment stops moving (often downhill or where water slows)

deposition

Types of sediment → broken pieces

clastic

Types of sediment → dissolved in water

chemical

Depositional environments → land/freshwater

continental

Depositional environments → ocean

marine

Depositional environments → coasts

transitional

What color sediments do hot or dry environments typically produce?

red

What kind of sediments do wet environments typically produce?

dark

Identifying depositional environments → grain size, roundness, etc.

rock type

Identifying depositional environments → arrangement of grains in 3D

sedimentary structures

Identifying depositional environments → remains of past life

fossils

What rock type are coral reef environments made of?

limestone

Order of rock tyoes: distance from shore

(closer → offshore)

sandstone, shale, limestone

To tell lakes and swamps apart from oceans, look at ______.

fossils

Rock types: distance from shore

(closest → farthest)

sands, silts, coral, sands-clays, clays, oozes and evaporites

What groups of corals dominated the late Paleozoic?

rugose, tabulate, stromatoporoids

What groups of corals dominated the early Paleozoic?

archaeocyathids and stromatolites

What groups of corals are dominating today?

scleractinian

Dating: order of events

relative age

Dating: numbers (often years before the present)

absolute age

What is an indicator that you have some sort of time lost?

unconformity

Matching rock layers from one place to another

correlation

Different fossil species lived at different times

• correlation based on same age, not same rock type

• even works across continents

fossil succession

What makes a good index fossil?

lived in many places, common, existed for short time

An attempt to fit Earth’s history into a short time and believed that rocks formed from sudden global disasters, not slow sediment deposition.

catastrophism

The belief that ancient rocks formed the same way as modern ones

• “The present is the key to the past”

• James Hutton (1726-1797)

uniformitarianism

The belief that extinction happens due to slow processes that occur normally in nature

gradualism

An igneous rock formed nowhere on earth today

komatiite

Debris from an asteroid impact

tektites

_____ age

• Benefits: easy to figure out, helps test cause and effect

• Downside: not precise

relative

_____ age

• Benefits: can say how fast things happened and how often

• Downside: difficult, expensive, not always possible

absolute

The study of rock layers

stratigraphy

Rules → rock layers form horizontally; any tilting happened later

rule of original horizontality

Rules → younger rocks form on top of older rocks

rule of superposition

Rules → igneous intrusions and fault lines cut through older rocks

rule of cross cutting relationships

Two atoms with the same number of protons are the _______.

same chemical element

Two atoms of the same chemical element with a different number of neutrons are _________.

different isotopes

Stable; no change over time

carbon 12 and 13

Radioactive isotope; falls apart because the number of neutrons makes the atom unstable

carbon 14

Something is kicked out of the atom to balance the number of protons and neutrons

• parent isotope changes the daughter isotope of a different element

radioactive decay

The time it takes half the parent isotope in a sample to decay into the daughter isotope

• (rate of decay)

half life

The % of parent isotope remaining is used to find the number of half-lives that have passed

radiometric dating

Limitations of radiometric dating: works for ________ because the mineral crystals are new when the rock forms

igneous rocks

Limitations of radiometric dating: does not work for most _________ because the crystals were part of older rocks

sedimentary rocks

Limitations of radiometric dating: can only measure back ______ half-lives before there is not enough parent isotope left to measure

7 to 10

Structure of the earth from outer to inner

crust, mantle, outer core, inner core

Earth, not true sphere

oblate spheroid

Continental crust

granite

Is the continental crust denser or less dense?

less dense

Is the oceanic crust denser or less dense?

denser

Oceanic crust

basalt

Mantle

convection

Parts of the crust moving in different directions

tectonic plates

• crust and uppermost mantle

• hard, more brittle parts, moves around as tectonic plates

lithosphere

• mantle immediately underlying the lithosphere

• sufficient heat and pressure that it flows more like a fluid/plastic

• lithosphere plate ‘floats’ on top of it

asthenosphere

Plate boundaries → moving apart

divergent

Plate boundaries

• volcanic eruptions make new crust at mid-ocean ridge

• plates move apart, and no oceanic lithosphere forms

• make new crust

divergent

Plate boundaries → moving past

transform

Plate boundaries

• no volcanoes

• nothing is pushed up or down

• no mountains

transform

Plate boundaries → moving together

convergent

Plate boundaries

• movement must be up or down

• when two plates collide, less dense crust goes over denser crust

• continental over oceanic

• younger oceanic crust over older

convergent