Geology Final

What does a geological map show?

Rock types

What are the 4 main parts of a geological map?

Map

How is a stratigraphic column ordered?

Oldest at bottom → youngest at top

What is stratigraphy?

Study of rock layers and their order in time

What does a map scale of 1:1

000

What does a larger scale map show?

More detail

What is strike?

Direction of a horizontal line on a plane

What is dip?

Angle a plane slopes downward

What type of stress causes normal faults?

Extension

What type of stress causes reverse faults?

Compression

What type of fault involves sideways motion?

Strike-slip fault

What are the 3 types of dating?

Relative

What is relative dating?

Determining older vs younger relationships

What is absolute dating?

Determining numerical age (millions of years)

What is the principle of superposition?

Oldest layers at bottom

What is original horizontality?

Layers form flat initially

What is cross-cutting relationships?

Feature that cuts is younger

What is faunal succession?

Fossils appear in predictable order

What is an unconformity?

Gap in geological record

What is radiometric dating based on?

Radioactive decay of isotopes

What isotope is used for very old rocks?

U-Pb or K-Ar

What is the limit of carbon-14 dating?

~50

When does carbon dating start?

At death of organism

What is half-life?

Time for half of radioactive atoms to decay

What does a short half-life mean?

Faster decay

What are the 3 main rock types?

Igneous

What are igneous rocks?

Formed from cooled magma/lava

What are sedimentary rocks?

Formed from deposited sediments

What are metamorphic rocks?

Rocks changed by heat/pressure

What is a mineral?

Naturally occurring

How is hardness measured?

Mohs scale

What is the hardness of quartz?

7

What mineral reacts with acid?

Calcite

What is cleavage?

Break along flat planes

What is fracture?

Irregular break

What is streak?

Powder color of mineral

What is lustre?

How light reflects off mineral

What is a solid solution?

Mineral with variable composition but same structure

How many major tectonic plates are there?

7

What boundary creates crust?

Divergent (constructive)

What boundary destroys crust?

Convergent (subduction)

What boundary slides past?

Transform

What is destroyed at subduction zones?

Oceanic crust

What formed the Himalayas?

Continental collision

What boundary is in California?

Transform

What drives plate motion the most?

Slab pull

What are other drivers of plate motion?

Ridge push

What is the thickness of oceanic vs continental crust?

Oceanic 5-10 km

Which crust is denser?

Oceanic

Why doesn't continental crust subduct easily?

Less dense

What are magnetic stripes evidence of?

Seafloor spreading

Where are magnetic stripes found?

Ocean floor

What is Pangea?

Ancient supercontinent

What is Panthalassa?

Superocean surrounding Pangea

What causes continents to break apart?

Rifting and plate tectonics

What evidence supports continental drift?

Fossils

What is an orogeny?

Mountain-building event

What ocean closed in the Caledonian orogeny?

Iapetus Ocean

What ocean closed in the Variscan orogeny?

Rheic Ocean

What are the 5 climate zones?

A tropical

Why is it hotter at the equator?

More direct solar radiation

Why are deserts at ~30° latitude?

Descending dry air (Hadley cells)

Why is Ireland warmer than Canada?

Gulf Stream

What is an icehouse climate?

Cold period with ice sheets

What is a greenhouse climate?

Warm period with little ice

What are glacial-interglacial cycles?

Alternating cold and warm periods

What happens to sea level during glaciation?

Falls

What landforms are formed by glacial erosion?

U-shaped valleys

What landforms are formed by glacial deposition?

Moraines

What shaped Ireland's modern landscape?

Ice sheets