Unit 6 Exam-Planet Earth Forms and Features
Why was Wegener's hypothesis of continental drift originally rejected?
Wegener had no way to explain how the continents moved
What is a constructive force? Example
Constructive forces build up the Earth's surface (Mountains)
Describe continental crust
Continental crust is less dense, contains rocks like granite, and has an average thickness of 40 km
What is the Richter Scale?
The Richter Scale rates earthquakes based on measurements of the times and amplitudes of seismic waves
Mineral Color
The color of a mineral
What is a mineral's streak?
The color of a mineral's powder
Mineral Streak
The color of a minerals powder
What is continental drift?
The continents were once joining a supercontinent which then broke into pieces and moved apart
How is a fold different than a fault?
A fold forms when rocks are squeezed together but don't break. A fault is when two slabs of rocks on either side move in relation to each other.
What is a tsunami?
A giant wave usually causes by an earthquake beneath the ocean floor
Mineral Density
A minerals mass divided by it's volume
What is a seismograph?
An instrument that measures seismic waves.
Why are coal, brick, concrete not minerals?
Coal comes from plants and the others are mixtures from materials
What causes plates to move?
Convection Currents
Plate boundary where subduction occurs?
Convergent Boundary
What is sea-floor spreading?
Creates new oceanic crust at mid-ocean ridges
What is a destructive force? Example
Destructive forces slowly break down the Earth's surface (Weathering and erosion)
What is plate tectonics?
Earth's lithosphere broken into larger pieces or plates that hold the continents/oceans and move slowly
What are extrusive igneous rocks?
Extrusive rock forms above the surface,fine-grained crystal structure, and they cool very quickly
Mineral Fracture
How a mineral breaks
Mineral Luster
How a mineral shines or reflects
What is a mineral's luster?
How a mineral shines or reflects
Crystal Structure
How atoms and molecules are arranged
How is igneous rock formed? Describe it.
Igneous rock is formed by the hardening of magma or lava. These rocks are shiny, glass-like, and have tiny holes/spaces.
How are rocks classified?
Igneous, Sedimentary, and Metamorphic
What are intrusive igneous rocks?
Intrusive rock forms underground in the Earth's crust from magma,they have coarse-grained crystal structures,these are larger than the extrusive rock, and they cool very slowly.
Describe the movement of P waves
Longitudinal waves that compress and expand the ground like an accordion, fastest seismic waves, and can travel through both solids and liquids
What is gneiss?
Metamorphic rock with crystals arranged in parallel bands or layers
How is metamorphic rock formed? Describe it.
Metamorphic rocks are formed from heat and pressure. These rocks have ribbon-like layers.
Where is new ocean crust formed?
Mid-Ocean Ridges
Why did the New Madrid Seismic Zone form?
North America almost broke apart about 600 million years ago, where a deep rift valley formed causing a large fault system in this region.
Describe oceanic crust
Oceanic crust is more dense, contains rocks like basalt, and the average thickness is 7 km.
Which part of the Earth's core is thought to be liquid?
Outer Core
How is sedimentary rock formed? Describe it.
Sedimentary rock is formed by being compressed and cemented. These rocks are brittle and crumble easily.
What are clastic rocks?
Sedimentary rocks formed from broken fragments of other rocks
What compounds primarily make up the earth's crust and mantle?
Silicates, aluminum, iron, and calcium
What in the Earth's crust causes faults and folds?
Tectonic plates moving and causing stress
Describe the Modified Mercalli Scale
The Modified Mercalli Scale ranges from 1-12 and is based on observations of the intensity of ground shaking and damage
Describe the Moment Magnitude Scale
The Moment Magnitude Scale gives the amount of energy released by an earthquake. Each unit increase on this scale represents about 32 times increase in energy
What is an earthquake?
The movement of the lithosphere that releases a large amount of energy
Mineral Hardness
The resistance of a mineral to scratching
What is a minerals hardness?
The resistance of a mineral to scratching
What is geology?
The study of Earth's composition and structure
What is Pangaea?
The supercontinent that Wegener hypothesized that formed well over 200 million years ago
What is the epicenter of an earthquake?
This is the point directly above the focus of an earthquake
How do trenches form?
Trenches are formed through subduction when the oceanic plate is subducted under the oceanic plate
Mineral Cleavage
Type of fracture
What is a fault?
When 2 slabs of rock move in opposite directions a fault will occur along the plate boundary.
What is subduction?
When old oceanic plates sink into the mantle
What is a divergent boundary?
When plates are moving away from each other.
What is a convergent boundary?
When plates are moving towards each other.
What is a transform boundary?
When plates slide past each other.
What is the focus of an earthquake?
Where the earthquake originates in the crust
What is a mineral?
a naturally occurring, inorganic solid with a crystal structure and a characteristic chemical composition.
