Types of Rocks
This type of rock is formed by layers building up over time.
Sedimentary rock
Are weathering and weather the same thing?
Name the four ways erosion typically occurs
Wind, Water, Ice, and Gravity
Deposition is the process where sediments are ____________.
Dropped off after erosion
Sedimentary rocks and igneous rocks can form on the surface of Earth. Why can't metamorphic rocks?
They need heat and pressure higher than the surface can produce.
This rock requires both high pressure and high heat to form.
Metamorphic rock
Name the two categories of weathering
Chemical and mechanical/physical
Why can't erosion happen before weathering?
Because a rock needs to be broken apart before the pieces can move
These two landmarks often form as rivers mature, slow down, and drop their sediment load.
Sandbars and river deltas.
Timmy is poking around in a dried up lake bed. He finds small shiny objects that look sort of like rocks all over the place. What is Timmy seeing?
Minerals formed by evaporation, possibly crystals.
This type of rock can form so fast that it still has air bubbles trapped inside sometimes.
Igneous rock
The statue of liberty turning green over the past two centuries instead of her original bright copper color is an example of what kind of chemical weathering?
Oxidation
Which part of the state of Massachusetts is evidence of glacial activity in the past?
Cape Cod is the sediments dumped by a moving glacier.
Deposition occurs when the forces of erosion have less energy than these two forces.
Gravity and friction
Convection currents in the mantle move tectonic plates in this way:
Hot molten rock rises up to the bottom of the crust, pushing against the tectonic plates and causing them to slide along the surface of the mantle.
This two step process is the smallest loop in the rock cycle (which rock can turn back into the ingredients that made it?)
Sedimentary rock can weather and erode into sediments, which can compress and cement back into sedimentary rock.
Name two ways that living organisms can weather rocks
Burrowing for animals and root wedging for plants
Why are beaches often the same color as the rocks on land nearby?
Beaches are made of sand that has eroded off nearby rocks before being deposited on the beach
Explain why a rock cannot be deposited on a mountain top through normal erosion events.
Gravity always pulls objects towards Earth, and normal erosion events do not have the force needed to move a rock back up a mountain.
Fossils are found almost always in sedimentary rocks and very rarely in igneous rock, but NEVER in metamorphic rock. Why is that?
Metamorphic rock forms deep in the Earth, below where animals and plants can live. The heat and pressure would destroy any fossils found in the sedimentary rocks that get pushed that deep.
List the steps needed to turn a sedimentary rock into an igneous rock (3 steps total)
1 Sedimentary rock is exposed to high heat and pressure, forming metamorphic rock.
2 Metamorphic rock is melted into magma
3 Magma or lava cools and hardens into igneous rock
How are chemical weathering and physical weathering different?
Chemical weathering breaks down chemical bonds in a rock, physical weathering only breaks the rock into smaller pieces
How does a mushroom rock form?
Wind slowly carves into a rock, weathering and eroding the base of it faster than the top, leaving a mushroom shaped rock that will eventually fall over when the base erodes too much.
Why are seaside deposition sites like sandbars and barrier islands important for humans?
They provide a buffer between human homes and the eroding force of the ocean, reducing the amount of energy that reaches the shore.
A tree growing in a sidewalk on a hill breaks the concrete sidewalk. The broken chunk rolls down the hill, falls in a river, and is dumped on a sandbar a mile away. Describe what happened using specific weathering, erosion, and deposition terms.
Root wedging weathers the rock to break it.
Gravity pulls the rock down the hill, eroding it.
(Bonus points for saying gravity might also be weathering the rock as it rolls, breaking more pieces off)
The river water pushing the rock downstream is more erosion.
Finally, the river deposits the rock on the sandbar as the forces of gravity and friction overcome the eroding force of water.