Key Idea: The surface of the earth is changed as rock material is broken, carried, and dropped in new locations.
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Small changes to the surface of the earth caused by wind and water can add up to large changes over long periods of time (i.e., over thousands to millions of years).

These items have been aligned to more than one key idea. To view the sub-ideas click on a key idea below.

  • The surface of the earth is changed as rock material is broken, carried, and dropped in new locations.

    Students are expected to know that:

    1. Wind and water (including glaciers, and water from rain, rivers, streams, and oceans) break, carry, and drop rocks as they move.
    2. The rock that is broken includes earth’s solid rock layer (bedrock) and loose rocks that range from large boulders to rocks so small that they can only be seen with a microscope (i.e., smaller than sand). These rocks are carried and dropped in new locations by wind and water, and they can hit and break other rocks as they are moved.
    3. The breaking, moving, and dropping of rock material makes mountains smaller, changes the shape of valleys and makes them deeper, and changes the shape of cliffs and coastlines and paths of rivers. The motion of wind and water causes these changes by removing rock material from one place and adding rock material in another. These changes can occur anywhere on or near earth’s surface, including under lakes, rivers, and oceans.
    4. Both slow-moving and fast-moving water can break and can move rocks, and both large volumes and small volumes of water can move and break rocks. Both slow-moving and fast-moving wind can move and break rocks.
    5. Rock can be broken when plant roots grow into cracks in the solid rock layer and cracks in loose rocks.
    6. Because water expands when it freezes, rock can be broken when water freezes in cracks in rocks.
    7. Rock can be worn away by dissolving. As water moves across and through the solid rock layer and loose rocks, it dissolves minerals that make up the rock and carries them away. The rock left behind then has less mass.
    8. Minerals that are dissolved in water can stay dissolved as the water flows over long distances, or the minerals can come out of solution and be deposited as solid minerals along the water’s path.

    Boundaries:

    1. The terms “weathering” and “erosion” are not used. All processes that involve the breakdown of rock material are described as “wearing away.”
    2. Students are not expected to know the different effects of wind and water on different rock types.
    3. Students are not expected to know which minerals dissolve easily in water, how minerals are dissolved, or how dissolved minerals are deposited as solid minerals.
    4. Students are not expected to know that in addition to the breakdown processes that are mentioned specifically, rocks also break down in other ways (such as by chemical reactions that change minerals).
    5. Students are not expected to distinguish mechanical from chemical processes of wearing away rock material.
    6. This topic exclusively addresses wearing away of rock material. Students are not assessed on the wearing away, moving, and dropping of soil (as distinct from rock material) as part of this topic.
    7. At the middle school level, this topic treats wind and water themselves as the agents of erosion, and it does not specifically address the fact that rocks carried by the wind and water are the primary cause for erosion.
    8. Ideas about earth’s outer rock layer are assessed in the topic of plate tectonics and, therefore, are not assessed as part of this topic.
  • Small changes to the surface of the earth caused by wind and water can add up to large changes over long periods of time (i.e., over thousands to millions of years).

    Students are expected to know that:

    1. Wind and water continuously wears away, moves, and drops rock material, even if it is by such small amounts that the changes cannot be seen without the help of instruments.
    2. Changes to the earth’s surface by wind and water that occur over relatively short time periods can add up to very large changes over long time periods. Because mountains and valleys are so large, and because even changes that occur over a year are relatively small compared to the size of the mountain or valley, it often takes many millions of years for wind and water to cause large changes to their shape and size.
    3. As a result of the continuous action of wind and water, all places on earth look different today from how they looked in the past and from how they will look in the future.
Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID
Number
Knowledge Being Assessed Grades
6–8
Grades
9–12
Select This Item for My Item Bank

WE056001

The solid rock of mountains was being worn down by wind and water millions of years ago, and it is being worn down by wind and water today.

68%

70%

WE026004

Moving water continuously wears down earth's solid rock layer, which changes the shape of a valley even if you cannot see it happening.

63%

69%

WE063001

Wind wore away the solid rock of valleys millions of years ago and continues to wear away the solid rock of valleys today.

59%

66%

WE031002

It takes many millions of years to wear away a mountain until it is almost flat.

59%

66%

WE062002

The solid rock of valleys was being worn away by wind millions of years ago, and it is being worn away by wind today.

61%

60%

WE025005

Wind and water can wear away the solid rock of a mountain over many millions of years.

58%

61%

WE018003

Moving water continuously wears down earth's solid rock layer whenever water is moving over the rock, even if you cannot see it happening.

45%

52%

WE019003

Whenever wind moves against the solid rock of a mountain, a little bit of the rock is worn away, even if you cannot see it.

42%

43%

WE048001

Water can gradually wear away the solid rock of mountains as much as thousands of feet over many millions of years.

36%

42%

WE039002

Water can gradually wear away the solid rock of river valleys as much as thousands of feet over millions of years.

36%

40%

WE059001

Rain wears away very small amounts of the rock of a cliff whenever the rain falls.

37%

37%

WE050001

Wind can gradually wear away the solid rock of river valleys as much as thousands of feet over millions of years.

35%

37%

WE049001

Wind can gradually wear away the solid rock of mountains as much as thousands of feet over many millions of years.

36%

35%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

WEM107

Wind can wear away the solid rock of mountains only a small amount (feet or inches) over millions of years, not thousands of feet (AAAS Project 2061, n.d.).

55%

55%

WEM095

Wind can make a valley deeper by only a small amount (feet or inches) over millions of years (AAAS Project 2061, n.d.).

55%

55%

WEM094

Water can wear away only a small amount of a mountain's height (feet or inches) over millions of years (AAAS Project 2061, n.d.).

55%

53%

WEM091

It takes rain a long time to wear away solid rock, even very small amounts that you cannot see (AAAS Project 2061, n.d.).

54%

53%

WEM096

Water can wear down the solid rock of a river valley only a small amount (feet or inches) over millions of years (AAAS Project 2061, n.d.).

54%

52%

WEM030

Wind can only wear down solid rock over long time periods. Changes are not happening over short time periods (i.e., a day or a year) (AAAS Project 2061, n.d.).

50%

48%

WEM086

Moving water can only wear down solid rock over long time periods. Changes are not happening over short time periods (i.e., a day or a year) (AAAS Project 2061, n.d.).

47%

42%

WEM067

Moving water can only change the surface of the earth over long time periods. Changes are not happening over short time periods (i.e., a day or a year) (AAAS Project 2061, n.d.).

33%

27%

WEM105

Wind is wearing away the solid rock of valleys today but did not wear away the solid rock of valleys in the past (AAAS Project 2061, n.d.).

27%

21%

WEM104

Wind wore away the solid rock of valleys in the past but is not wearing away the solid rock of valleys today (AAAS Project 2061, n.d.).

25%

20%

WEM022

Wind and water only change the surface of the earth during rare events, such as huge storms (AAAS Project 2061, n.d.).

20%

20%

WEM050

It only takes hundreds of years for wind and water to wear away the solid rock of a mountain (bedrock) so that the mountain is almost flat (AAAS Project 2061, n.d.).

18%

17%

WEM070

Solid rock was being worn away by wind many years ago, but it is no longer being worn away by wind today (AAAS Project 2061, n.d.).

16%

16%

WEM062

Wind and water changed the surface of the earth in the past but are no longer changing the surface of the earth (AAAS Project 2061, n.d.).

16%

12%

WEM071

Solid rock is currently being worn away by wind, but it was not being worn away by wind many years ago (AAAS Project 2061, n.d.).

13%

13%

WEM051

Landforms can change in size, but not by the motion of wind and water (AAAS Project 2061, n.d.).

12%

10%

WEM063

Wind and water are changing the surface of the earth today but did not change the surface of the earth in the past (AAAS Project 2061, n.d.).

10%

13%

WEM028

Erosion can wear away solid rock a little bit but could never have a big effect on the surface of the earth such as leveling mountains or carving valleys (AAAS Project 2061, n.d.).

11%

10%

WEM106

It takes only a short time (tens of years) for wind and water to wear down the solid rock of a mountain so that the mountain is almost flat (AAAS Project 2061, n.d.).

11%

8%

WEM092

Rain cannot wear away solid rock (AAAS Project 2061, n.d.).

9%

9%

WEM072

Wind cannot wear away solid rock (AAAS Project 2061, n.d.).

9%

10%

WEM090

Water cannot wear away solid rock (AAAS Project 2061, n.d.).

9%

7%

WEM087

Moving water cannot wear down solid rock (AAAS Project 2061, n.d.).

8%

7%

WEM038

Wind and water cannot wear away the solid rock of a mountain (AAAS Project 2061, n.d.).

7%

11%

WEM068

Moving water cannot wear away solid rock to change the shape of a valley (AAAS Project 2061, n.d.).

4%

8%

Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.