Geos 2104 test 1

Absolute time

How old is a rock or geological entity

Radioactive dating techniques

Break the rock into ions ad measure with mass spectrometer both the number of parent atoms and number of daughter

Rocks have to contain the right amount of parents and daughter ions

Why are many rocks very difficult to date?

Relative time

Somethings age related to the age of something else

Uniformitarianism

Geological processes act the same over time

Sediment

Rock particles

Original horizonality

Sediments were laid down in layers that were originally horizontal

Superposition

Younger layers were originally on top of older layers

Cross-cutting relationships

The rock is older than the structure that deformed it

The rock was created after the species evolved and before it went extent

How do fossils tell us when a rock was around?

Geologic time scale

A scale showing relative time

4600 million years

How old is Earth?

3500 million years

How old is the earliest fossil cells?

1100 million years

How old are the oldest major Virginia rocks?

300-400 million years

How old are the Appalachian Mountains?

65 million years

How long ago was the extinction of dinosaurs?

570 million years

How old were the first shells?

400 million years

How old was the first land plant?

0.01 million years

When was the end of the last ice age?

0.5 million years

How old are homo sapiens?

Inner core

1/3 of core

Outer core

2/3 of core

1/2 of Earth's radius

How much of Earth's radius does the core make up?

Fe and Ni

What is the core made up of?

Mantle

5/6 of Earth's volume

5/6

How much of Earth's volume does the mantle make up?

Mg

Fe

Continental crust

20-70 km deep

Oceanic crust

4-7 km deep

Lithosphere

cold

Silicate-rich lighter minerals

What are the continental crust and oceanic crust made up of?

Asthenosphere

Hot

Mid-ocean ridges

Where are earthquakes?

Mid-ocean ridges

convergent plate boundaries

Mid-ocean ridges

Mountain ranges on the ocean floor at divergent plate boundaires

Ocean trenches

Upside down mountains under the ocean

Plate tectonics

Plates that are relatively strong and ridged

Lithosphere

What part of the earth is a plate a part of?

Continental drift

Continents moving

cm/year

speed of fingernails and hair

Divergent plate boundaries

Where in plate tectonics does extension occur?

Seafloor spreading

Mantle comes up and creates more lithosphere

Convergent plate boundaries

Where in plate tectonics does compression occur?

Subduction

The lithosphere is going back down into the mantle (oceanic goes down) so only when one is ocean

Collision

When there are two continents

Transform faults

Where does boundary-parallel motion occur?

Transform fault

When plates just slide against one another

Heat

What drives plate tectonics?

Because kinetic energy was turned into heat energy when the planet was formed

Why is it hot inside the Earth?

Mantle convection

Rising when warm and falling when cool so the mantle flows at speeds of cm/year solid but soft enough to flow

Paradigm

A way of thinking and understanding in science paradigms change through a revolutionary new theory or law

Law

a fundamental

Theory

A hypothesis accepted after thorough testing

Hypothesis

model

makes predictions that are testable

should be powerful

simple

New crust is formed

cools and gets stronger

Mid-ocean ridges

Where does seafloor spreading occur?

Continent-continent collision zone

Where does mountain building occurs?

Pangaea

Super continent formed by continent-continent collisions 290 million years ago

Continents broke apart

200 million years ago-present

Between 290-320 million years ago

How and when did the Appalachians form?

Middle-oldest

east-younger

Iron

Oxygen

Core

mantle

Mantle

crust

Mantle

crust

Mantle

crust

Oxygen

silicon

Rock

Attached assemblage of minerals

Mineral

Natural

Crystal

Repeated regular arrangement of specific elements in a solid

Hand sample

a rock you can pick up by hand and see with your eyes

Thin section

Sliced rock (1/100th of an inch) and then put under a microscope to identify it

Geochemistry

Uses chemical methods to identify a mineral (mass spectrometer)

Geophysics

Uses physical properties to identify a mineral (speed of sound)

Silicates

carbonates

sulphates

oxides

hydroxides

halides

What are the different mineral groups you need to know?

Silica octahedra or tetrahedra + cations

the earth is mostly made of silicates

Bridgmanite

Octahedra

Olivine

Tetrahedra

Pyroxene

Tetrahedra

Garnet

Tetrahedra

Amphibole (e.g. horneblende)

Tetrahedra

Mica (e.g. biotite

muscovite)

Clay

Sheet

Feldspar

3D framework

Quartz

3D framework

CO₃²⁻+ cations (triangles)

SO₄²⁻+ cations (tetrahedra)

Calcite

CaCO₃

Gypsum

CaSO₄ 2H₂O

Apatite

Ca₅(PO₄)₃(OH

O²⁻+ cations

OH⁻+ cations

Hematite

magnetite

Pyrite

FeS₂

Rust

FeOOH

Cl⁻

F⁻

Halite

NaCl