Gizmos -River Erosion - complete answer key (2022) A+ Guide Already Graded A+ 100% GUARANTEED A ✔

Student Exploration: River Erosion

Vocabulary: cutbank, discharge, erosion, flood,

floodplain, meander, meandering river, oxbow lake,

point bar, river speed, sediments, slope,

streambank, streambed, tributary, weathering

Prior Knowledge Questions (Do these BEFORE

using the Gizmo.)

1. The image above shows a raging mountain river in full flood. What do you think is making

the water brown in color? The dirt from the mountain is making the river brown.

2. What impact do you think the flooding river will have on the surrounding landscape? The

impact that the flooding river will have on the surrounding landscape I think is that the soil

 will not me stable and landslide have a higher possibility of happening.

Gizmo Warm-up

If you stand by the bank of a river, it may seem that very little is

happening. But over thousands and even millions of years,

rivers can have a profound effect on the landscape. In the River

Erosion Gizmo, you will see how rivers move materials and how

they affect landscapes.

To begin, check that Mountain stream and Short-term erosion are selected. The Gizmo

shows a typical stream that is moving through a hilly area.

1. The two movie cameras ( ) allow you to observe different parts of the stream up close.

Click on the left movie camera. What do you see? On the left movie camera, I see under the

 surface on the river and I see a fish swimming.

2. Sediments are small rock fragments such as sand or pebbles. What evidence do you see

that sediments are being transported? On the right camera, sediments are falling into the

 river and the river’s current moving the sediment along with it.

3. Now select the right movie camera to see the bank of the mountain stream. What is

happening to sediments on the bank? The sediments on the bank are being push/

 transported by the river’s current.

Activity A:

Mountain streams

Get the Gizmo ready:

 Check that Mountain stream and Short-term

erosion are selected.

 If necessary, click outside the circle to close the

zoomed-in view.

Introduction: Erosion occurs when sediments and other materials are moved from one place

to another. Along with weathering, which is the breakdown of large rocks into smaller

sediments, erosion can have a profound impact on the landscape.

Question: How does river erosion affect landscapes in the mountains?

1. Label: First, get to know some of the

different parts of a mountain stream. Turn

on Show labels. Label the image to the

right, then fill in the word that goes with

each description.

A small stream that flows into a larger

stream: Tributary

A place along a stream where water drops

straight down: Waterfall

A letter that describes the shape of a typical mountain valley: V-shape valley

The side of a stream: Streambank The bottom of a stream:

 Streambed

2. Observe: Turn off Show labels. Next to “Release barrel,” click Play ( ). Observe how fast

the barrel moves as it floats down the stream.

What happens when the barrel goes over the waterfall?

When the barrel goes over the waterfall, the barrel quickly tumbles down with tipping

 over.

3. Calculate: The two red flags are 100 meters apart. The time at which the barrel passes the

flag is shown. Remember, there are 60 seconds in a minute.

A. How many seconds did it take for the barrel to go 100 meters? It takes the barrel 91

 seconds to go 100 meters

B. To find the barrel’s speed, use a calculator to divide the distance traveled (100 m) by

the time it took the barrel to float 100 m. The units are meters per second (m/s).

What is the speed of the barrel? 100/91= 1.098 The speed of the

barrel is about 1.1 m/s.

(Activity A continued on next page)