Constructive and Destructive Processes Practice

Sort each description into the correct category.

Groups:

(a) Physical Weathering

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(b) Chemical & Biological Weathering

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(c) Erosion

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(d) Deposition

• As floodwaters recede, the slowed water flow leaves behind the sediment that was moved.

• Acid rain reacts with limestone, dissolving the rock and forming caves.

• A fast-flowing river removes sediment at a river cutbank.

• Glaciers melt and leave behind piles of rock and sediment called moraines.

• Water freezes inside cracks of a rock, expands, and breaks the rock apart.

• Rocks in a stream bump and grind against each other, slowly wearing down into smaller pieces.

• Iron in rocks reacts with oxygen and water, creating reddish-brown rust that weakens the rock.

• A landslide is moving rocks and sediment down a steep hillside.

Answer explanation

• Physical weathering – The breaking down of rocks into smaller pieces without changing their chemical makeup (e.g., freezing and thawing cracks rocks).

• Chemical weathering – The breakdown of rocks through chemical reactions that change the rock’s composition (e.g., acid rain dissolving limestone).

• Erosion – The movement of rock, soil, or sediment from one place to another by wind, water, ice, or gravity.

• Deposition – The settling or laying down of sediments after they are carried by erosion (e.g., sand building up in a river delta).

Tags

NGSS.MS-ESS2-2

Match each weathering or erosion process with the correct description.

• Gravity

• Minerals in rock are chemically broken down as water changes them into new substances or carries them away in solution.

• Plant Processes

• Water freezes in cracks, expands, and forces rock apart over time.

• Water Dissolving

• Rocks and soil move downslope directly, pulled without another agent carrying them.

• Stream Flow

• Rocks are broken apart as roots grow into cracks and expand them.

• Ice

• Liquid water carries sediments downhill in channels, carving valleys and transporting material.

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In Ioway Creek, (a)   happens when sand, pebbles, and ​ (b)   move along the bottom of the stream. During normal flow, the water has enough energy to push and roll mostly sand and some small pebbles. In a (c)   , however, the water moves much faster and has much more force, so it can drag and bounce ​ (d)   downstream. This reshapes the streambed and, when the floodwater subsides, it leaves behind a new ​ (e)   (and new rocks for students to find)!

• bedload transport
• flood
• beach
• dissolved load
• small rocks
• big rocks

Answer explanation

Bedload transport is when larger particles like sand, gravel, or pebbles move along the bottom of a stream by rolling, sliding, or bouncing. Dissolved load transport is when materials like salts and minerals are completely dissolved in the water—making them invisible but measurable with tools like TDS meters. During a flood, bedload transport increases because the faster, stronger water can pick up and move much larger and heavier particles than it normally can.

Tags

NGSS.MS-ESS2-1

Categorize the TDS measurements for each location (Ioway Creek, Groundwater, Distilled Water).

Groups:

(a) Ioway Creek

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(b) Groundwater Near Ioway Creek

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(c) Distilled Water

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(d) Tap Water

• Water is evaporated and re-condensed to separate the water from the dissolved minerals.

• 265 ppm (safe to drink!)

• 0-3 ppm

• 415 ppm

• 220 ppm (but not safe to drink)

• A mix of water that came from rain runoff and some groundwater flow.

• We get our drinking water from groundwater that is recharged by Ioway Creek.

• Water infiltrates into the soil and dissolves matter as it flows underground.

Answer explanation

Distilled Water - Very low dissolved load because it has been evaporated (leaving the salts behind).

Tap Water - What we drink out of the sink. In Ames, we get our water from groundwater, so it has high levels of dissolved solids (called hard water, this is actually generally healthy but leaves deposits in pipes).

Groundwater - Because groundwater is in the ground, it has high TDS levels (it is constantly dissolving rocks and sediments).

Ioway Creek Water - Because this water is partly from the groundwater and partly from rainwater (which has very little dissolved in it), the TDS measurements are "in between."

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NGSS.MS-ESS3-1

​ (a)   TDS (total dissolved solids) in groundwater indicates that water ​ (b)   minerals from rocks underground, a ​ (c)   because it breaks down and removes material. On the other hand, the fossils found on the creek’s beach show evidence of ​ (d)   , where dissolved minerals later ​ (e)   out of the water and filled in the remains of ancient organisms, preserving them in rock. Together, these examples show how water can both wear away Earth’s materials and build new features.

• High
• destructive process
• constructive processes
• precipitated
• dissolved

Answer explanation

Dissolution is a destructive force because water dissolves minerals in rocks, slowly wearing them away and creating features like caves or sinkholes. Precipitation of minerals from water is a constructive force because it builds up new solid material, such as forming stalactites and stalagmites in caves, cementing sediments into rock, creating geodes, or creating fossils out of bone.

Tags

NGSS.MS-ESS2-1

NGSS.MS-ESS2-2

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Where is erosion happening at a cutbank?

Answer explanation

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Match the descriptions to the location.

Groups:

(a) Location A

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(b) Location B

• Cutbank

• Erosion

• Faster Flow

• Slower Flow

• Deposition

• Point Bar

• Beach

Answer explanation

A cutbank is the steep, eroded outer edge of a river bend where fast-moving water scours and removes soil and rock. It’s formed by erosion, making it a destructive process in the landscape.

A point bar is the gently sloping deposit of sand or gravel that builds up on the inside of a river bend, where the water flows more slowly. It’s formed by deposition, making it a constructive process in the landscape.

Comparison: Cutbanks and point bars always form together on opposite sides of a meander—cutbanks show where the river is actively wearing away land, while point bars show where the river is building new land.

Tags

NGSS.MS-ESS2-2