Chemical Weathering
A metal-rich rock turns reddish-brown after being exposed to oxygen and water. What process occurred?
Oxidation
Water freezes inside a crack, expands, and makes the crack larger. What process is this?
Ice wedging/frost wedging
When acid rain reacts with and dissolves limestone, what type of weathering is occurring?
Chemical weathering
Name one agent that can cause erosion?
Water, wind, ice or gravity
What landform can form when a river deposits sediment where it enters a larger body of water?
Delta
What gas combines with water to form a weak acid that can dissolve some rocks?
Carbon dioxide
Rock scrape against each other as they move downstream in a river. What type of weathering is occurring?
Mechanical/physical weathering through abrasion.
A river carries sand and small rocks downstream. What process is occurring?
Erosion
Which agent or erosion is mainly responsible for moving a sediment downhill during a landslide?
Gravity
Why does sediment often build up on the inside of a river bend?
Water moves slower there, causing sediment to be deposited.
How does acid rain chemically weather rock?
It reacts with minerals in the rock and dissolves or changes them.
Why can repeated freezing and thawing eventually break a large rock apart?
Water enters cracks, freezes and expands repeatedly, making the cracks larger.
How can glaciers cause erosion?
Glaciers move across land and carry or scrape away rock and sediment.
Why does faster-moving water usually carry larger pieces of sediment than slower-moving water?
Faster water has more energy to move heavier larger sediment.
Why is point bar usually found on the inside of a meandering river bend rather than the outside?
Two identical limestone rocks are placed outside. One is in an area with frequent acid rain, while the other is in an area with little pollution. Which rock will chemically weather faster and why?
The rock exposed to acid rain because the acid reacts with and dissolves limestone.
A rock tumbles down a steep mountain and repeatedly collides with other rocks. Explain why it becomes smaller and smoother.
Repeated collisions cause abrasion, breaking off pieces and smoothing the rock.
A river curves around a bend. On which side of the bend is erosion usually greatest: the inside or outside? Why?
Outside, because the water moves faster there.
After a forest is cleared, a hillside begins losing large amounts of soil during rainstorms. Why did erosion increase?
Plant roots were no longer holding the soil in place, allowing runoff to carry it away.
A fast-moving river enters a calm lake. Predict what will happen to the sediment the river is carrying and explain why.
Sediment will be deposited because the water slows down and loses energy.
A scientist find that rocks in a warm, wet climate chemically weather faster than the same rocks in a cold, dry climate. Explain why.
Warm temperatures speed chemical reactions, and water helps chemical weathering reactions occur.
Two identical rocks are placed in different environments. Rock A experiences frequent freezing and thawing. Rock B stays at a constant warm temperature. Which will likely break apart faster and why?
Rock A because repeated freezing and thawing causes ice wedging.
A river carries gravel, sand, silt, and clay. When the river suddenly slows down, predict the general order in which these sediments will be deposited?
Gravel first, then sand, then slit, then clay.
A river becomes faster after several days of heavy rain. Predict how the amount and size of sediment being transported will change.
The river can transport more sediment and larger particles because the faster water has more energy.
Explain how erosion and deposition work together to change the shape of a meandering river over time.
Faster water erodes the outside/cut bank, while slower water deposits sediment on the inside/point bar, gradually changing the river's path.