Answers to the Geology Exam Review worksheet

Layers near the surface of the Earth (lithosphere, hydrosphere, biosphere, atmosphere)

What do the 4 prefixes mean? (litho-rock hydro-water bio-life atmos-air)
Rock cycle: how to read the rock cycle diagram

Describe two ways a sedimentary rock can form. an igneous rock weathers into sediment, erodes away, settles somewhere else, then is cemented and compacted into a sedimentary rock

Explain what turns an igneous rock into a metamorphic rock. heat and pressure

What are sediments? broken bits of rock that have been weathered
Formation of types of rocks (sedimentary, igneous, metamorphic)

Explain how each type of rock is formed. 

sedimentary: broken bits of rocks are pressed together and glued by minerals or other bits of rock

metamorphic: existing rocks are squeezed and heated, melting partially and morphing (changing) form
igneous: magma or lava cools, hardening into rock

What do sedimentary rocks contain that other types of rock do not? fossils
Properties of minerals: cleavage/fracture, luster, hardness, color, streak

Identify a mineral that has a green streak. pyrite

Identify a mineral that has cubic cleavage and tastes salty. halite

What properties would you need to observe to identify a mineral as calcite? bubbling with acid
Erosion – transportation of sediment after it is broken down by weathering

The forces that carry sediment (4 forces; 3 of them were demonstrated by sand in class) water, wind, glaciers, and gravity
Weathering (chemical and mechanical)

Explain how a pothole is formed.  A pothole is formed by ice wedging, which means that water seeps into a crack, then freezes and expands, wedging the rock apart.

Is the formation of a pothole mechanical or chemical weathering? physical

What is chemical weathering?  Chemical weathering is the breaking down of rocks where the composition of the rock is changed in the process.  This is different from physical weathering because physical weathering just makes rocks into smaller rocks.
Where fossils are found

In which type of rock are fossils mostly found?  Sedimentary
Relative ages of rocks

How does the age of fossils in the bottom layer of sedimentary rocks compare to the ages of fossils in the top layer?  The bottom layer is older than the top layer.
What the fossil record tells us

What can scientists infer by studying fossils of organisms that lived long ago? Scientists can infer what the characteristics of the climates and environments were.
Theory of Plate Tectonics

Alfred Wegener’s hypothesis:  The continents used to be connected and then have slowly moved apart to their current locations.

What fossils show about continental drift:  Fossils of some plants and animals can be found on more than one continent, showing that the continents used to be connected.
Convection Currents – movement that is created in a fluid when it is heated unevenly

Draw two convection currents in the mantle that are helping tectonic plates move.
Why one plate sinks under the other at a subduction zone

Draw a picture of one plate subducting under the other.

Label the plate that is more dense. The more dense plate is sinking under the continental plate.

Seafloor spreading

Who is Harry Hess?  What did he do to provide evidence for Wegener’s hypothesis?

Harry Hess used sonar to map the ocean floor.  He showed that there were ridges (mountains) and volcanoes on the seafloor, which provided evidence that new rock material was being created at the ridges, pushing the continents apart.
Measuring mass with a triple beam balance

Be able to measure mass to the nearest tenth of a gram.