Measure effects of weathering on rate of erosion - 4th Grade Science
Card 1 of 40
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They measured the soap after soaking for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. They observed bits of soap breaking off and floating in the water. They took final measurements and recorded them in the data chart below.
Based on this data, what had the most significant effect on the soap?
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They measured the soap after soaking for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. They observed bits of soap breaking off and floating in the water. They took final measurements and recorded them in the data chart below.
Based on this data, what had the most significant effect on the soap?
Tap to reveal answer
This observation is focused on the effect that weathering has on the rate of erosion. As wind and water break bits of material off, that material is moved to a new location. When looking at the data, there was a 45cm3 difference between the bar of soap at the beginning of the investigation and the end of soaking. When they measured the soap after spraying, it only had a volume of 2cm3, which was a decrease of 78cm3. Using the data from the observations, it can be concluded that spraying the soap has a more significant impact on its size and volume.
This observation is focused on the effect that weathering has on the rate of erosion. As wind and water break bits of material off, that material is moved to a new location. When looking at the data, there was a 45cm3 difference between the bar of soap at the beginning of the investigation and the end of soaking. When they measured the soap after spraying, it only had a volume of 2cm3, which was a decrease of 78cm3. Using the data from the observations, it can be concluded that spraying the soap has a more significant impact on its size and volume.
← Didn't Know|Knew It →
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They soaked the soap for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. Miranda noticed that when the soap was sitting in the water it was getting smaller but took a very long time. There was barely a change after the three hours. When they sprayed the bars of soap they broke down quickly and bits of soap began breaking off. They repeated the experiment with multiple bars of soap and saw the same results.
Does this process take a long time and how does your data show you the evidence?
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They soaked the soap for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. Miranda noticed that when the soap was sitting in the water it was getting smaller but took a very long time. There was barely a change after the three hours. When they sprayed the bars of soap they broke down quickly and bits of soap began breaking off. They repeated the experiment with multiple bars of soap and saw the same results.
Does this process take a long time and how does your data show you the evidence?
Tap to reveal answer
The natural process of weathering and erosion happens very slowly, and this investigation was no different. After Miranda's class has placed the soap into the standing water, they waited three hours and barely saw a difference in the size and volume. There was only a 45cm3 difference in the volume after three hours. It was not until moving water by way of the spray bottles did things speed up. Had Miranda's class just left the soap to be eroded, it could have taken more than one school day to complete the process.
The natural process of weathering and erosion happens very slowly, and this investigation was no different. After Miranda's class has placed the soap into the standing water, they waited three hours and barely saw a difference in the size and volume. There was only a 45cm3 difference in the volume after three hours. It was not until moving water by way of the spray bottles did things speed up. Had Miranda's class just left the soap to be eroded, it could have taken more than one school day to complete the process.
← Didn't Know|Knew It →
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They soaked the soap for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. Miranda noticed that when the soap was sitting in the water, it was getting smaller but took a very long time. There was barely a change after the three hours. When they sprayed the bars of soap, they broke down quickly, and bits of soap began breaking off. They repeated the experiment with multiple bars of soap and saw the same results.
What does this data tell you about moving water versus standing water and how it changes the landscape over time?
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They soaked the soap for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. Miranda noticed that when the soap was sitting in the water, it was getting smaller but took a very long time. There was barely a change after the three hours. When they sprayed the bars of soap, they broke down quickly, and bits of soap began breaking off. They repeated the experiment with multiple bars of soap and saw the same results.
What does this data tell you about moving water versus standing water and how it changes the landscape over time?
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. When reviewing the observations and data from Miranda's investigation, one may notice that running water (the spray bottle) eroded more material in a shorter period. When comparing moving water and standing water, there is a significant difference, and running water would change the landscape more quickly.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. When reviewing the observations and data from Miranda's investigation, one may notice that running water (the spray bottle) eroded more material in a shorter period. When comparing moving water and standing water, there is a significant difference, and running water would change the landscape more quickly.
← Didn't Know|Knew It →
Scientists are studying different cliff faces and how their rates of erosion are affected by the slope of the rock formation. DJ thinks that the steeper the cliff, the higher or faster the rate of erosion will be. Matt says it will be the opposite, that the steeper the cliff is, the lower or slower the rate of erosion will be. They know gravity pulls rocks down, and this will have an effect on the cliff's erosion rate. Based on the data chart below, who is correct, and why?
Scientists are studying different cliff faces and how their rates of erosion are affected by the slope of the rock formation. DJ thinks that the steeper the cliff, the higher or faster the rate of erosion will be. Matt says it will be the opposite, that the steeper the cliff is, the lower or slower the rate of erosion will be. They know gravity pulls rocks down, and this will have an effect on the cliff's erosion rate. Based on the data chart below, who is correct, and why?
Tap to reveal answer
DJ and Matt are both on the right track when they are thinking about rocks being pulled down and affected by gravity, but that is where the commonalities stop. DJ is correct in his thinking related to the steep rock cliffs. The steeper the cliff is, the sooner and faster it will be eroded. The steep slope allows the force of gravity to move more rock more quickly. When looking at the data, a trend can be seen, the higher the slope of the cliffside is, the sooner it will erode. A cliffside with a 30o slope will erode in 61 years compared to an 87o slope eroding in 24 years.
DJ and Matt are both on the right track when they are thinking about rocks being pulled down and affected by gravity, but that is where the commonalities stop. DJ is correct in his thinking related to the steep rock cliffs. The steeper the cliff is, the sooner and faster it will be eroded. The steep slope allows the force of gravity to move more rock more quickly. When looking at the data, a trend can be seen, the higher the slope of the cliffside is, the sooner it will erode. A cliffside with a 30o slope will erode in 61 years compared to an 87o slope eroding in 24 years.
← Didn't Know|Knew It →
Scientists are studying different cliff faces and how their rates of erosion are affected by the slope of the rock formation. Meredith wants to come up with a way to extend the amount of time that it takes for a cliff face to be completely eroded. What can Meridith recommend doing after reviewing the relationship between slope and erosion rate in the table below?
Scientists are studying different cliff faces and how their rates of erosion are affected by the slope of the rock formation. Meredith wants to come up with a way to extend the amount of time that it takes for a cliff face to be completely eroded. What can Meridith recommend doing after reviewing the relationship between slope and erosion rate in the table below?
Tap to reveal answer
Meredith can use this data table to look for a pattern or connection between the slope of the cliffside and the average erosion rate. Based on the measurements recorded, the lower the slope, the longer it takes for the cliff to erode. Meredith could suggest building the cliffside up to reduce the slope so that scientists could increase the amount of time it would take to erode. The steep slope allows the force of gravity to move more rock faster, so by reducing the slope, the rock will not move as quickly.
Meredith can use this data table to look for a pattern or connection between the slope of the cliffside and the average erosion rate. Based on the measurements recorded, the lower the slope, the longer it takes for the cliff to erode. Meredith could suggest building the cliffside up to reduce the slope so that scientists could increase the amount of time it would take to erode. The steep slope allows the force of gravity to move more rock faster, so by reducing the slope, the rock will not move as quickly.
← Didn't Know|Knew It →
The data table below shows the width of the beach measured every two years.
What natural process is likely causing the beach to become shorter in width each year?
The data table below shows the width of the beach measured every two years.
What natural process is likely causing the beach to become shorter in width each year?
Tap to reveal answer
The natural process of weathering and erosion happens very slowly. Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. In this example, erosion due to the ocean waves crashing onto the beach is washing away sand, causing it to be slowly moved out to sea, and the beach becomes shorter in width.
The natural process of weathering and erosion happens very slowly. Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. In this example, erosion due to the ocean waves crashing onto the beach is washing away sand, causing it to be slowly moved out to sea, and the beach becomes shorter in width.
← Didn't Know|Knew It →
The data table below shows the width of the beach measured every two years.
Based on the pattern, what will the width of the beach most likely be in year 11?
The data table below shows the width of the beach measured every two years.
Based on the pattern, what will the width of the beach most likely be in year 11?
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. The beach is eroding at a rate of 0.02 meters every two years. It can be predicted that the trend will continue, and in year 11, the beach will be 7.3 meters wide.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. The beach is eroding at a rate of 0.02 meters every two years. It can be predicted that the trend will continue, and in year 11, the beach will be 7.3 meters wide.
← Didn't Know|Knew It →
True or False: The effects of weathering on the rate of erosion cannot be measured.
True or False: The effects of weathering on the rate of erosion cannot be measured.
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. The effects of weathering on the rate of erosion can be measured and often is to determine if reconstruction or human intervention is needed to stop the weathering and erosion in areas.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. The effects of weathering on the rate of erosion can be measured and often is to determine if reconstruction or human intervention is needed to stop the weathering and erosion in areas.
← Didn't Know|Knew It →
Which example is NOT a direct cause of erosion?
Which example is NOT a direct cause of erosion?
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. Wind, water, and gravity can all move bits of broken rock and sediment. Temperature is not a direct cause of erosion. It plays an effect in the freezing and melting of water during the weathering process that breaks rocks apart.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. Wind, water, and gravity can all move bits of broken rock and sediment. Temperature is not a direct cause of erosion. It plays an effect in the freezing and melting of water during the weathering process that breaks rocks apart.
← Didn't Know|Knew It →
What is the best scientific method for determining if erosion is taking place?
What is the best scientific method for determining if erosion is taking place?
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. Measuring the area over time, taking photographs for comparison, and writing detailed observations are scientific methods for determining if erosion is taking place.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. Measuring the area over time, taking photographs for comparison, and writing detailed observations are scientific methods for determining if erosion is taking place.
← Didn't Know|Knew It →
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They measured the soap after soaking for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. They observed bits of soap breaking off and floating in the water. They took final measurements and recorded them in the data chart below.
Based on this data, what had the most significant effect on the soap?
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They measured the soap after soaking for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. They observed bits of soap breaking off and floating in the water. They took final measurements and recorded them in the data chart below.
Based on this data, what had the most significant effect on the soap?
Tap to reveal answer
This observation is focused on the effect that weathering has on the rate of erosion. As wind and water break bits of material off, that material is moved to a new location. When looking at the data, there was a 45cm3 difference between the bar of soap at the beginning of the investigation and the end of soaking. When they measured the soap after spraying, it only had a volume of 2cm3, which was a decrease of 78cm3. Using the data from the observations, it can be concluded that spraying the soap has a more significant impact on its size and volume.
This observation is focused on the effect that weathering has on the rate of erosion. As wind and water break bits of material off, that material is moved to a new location. When looking at the data, there was a 45cm3 difference between the bar of soap at the beginning of the investigation and the end of soaking. When they measured the soap after spraying, it only had a volume of 2cm3, which was a decrease of 78cm3. Using the data from the observations, it can be concluded that spraying the soap has a more significant impact on its size and volume.
← Didn't Know|Knew It →
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They soaked the soap for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. Miranda noticed that when the soap was sitting in the water it was getting smaller but took a very long time. There was barely a change after the three hours. When they sprayed the bars of soap they broke down quickly and bits of soap began breaking off. They repeated the experiment with multiple bars of soap and saw the same results.
Does this process take a long time and how does your data show you the evidence?
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They soaked the soap for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. Miranda noticed that when the soap was sitting in the water it was getting smaller but took a very long time. There was barely a change after the three hours. When they sprayed the bars of soap they broke down quickly and bits of soap began breaking off. They repeated the experiment with multiple bars of soap and saw the same results.
Does this process take a long time and how does your data show you the evidence?
Tap to reveal answer
The natural process of weathering and erosion happens very slowly, and this investigation was no different. After Miranda's class has placed the soap into the standing water, they waited three hours and barely saw a difference in the size and volume. There was only a 45cm3 difference in the volume after three hours. It was not until moving water by way of the spray bottles did things speed up. Had Miranda's class just left the soap to be eroded, it could have taken more than one school day to complete the process.
The natural process of weathering and erosion happens very slowly, and this investigation was no different. After Miranda's class has placed the soap into the standing water, they waited three hours and barely saw a difference in the size and volume. There was only a 45cm3 difference in the volume after three hours. It was not until moving water by way of the spray bottles did things speed up. Had Miranda's class just left the soap to be eroded, it could have taken more than one school day to complete the process.
← Didn't Know|Knew It →
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They soaked the soap for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. Miranda noticed that when the soap was sitting in the water, it was getting smaller but took a very long time. There was barely a change after the three hours. When they sprayed the bars of soap, they broke down quickly, and bits of soap began breaking off. They repeated the experiment with multiple bars of soap and saw the same results.
What does this data tell you about moving water versus standing water and how it changes the landscape over time?
Miranda's class was investigating how weathering affected the rate of erosion. They put chunks of bar soap in an aluminum foil tray and filled it about halfway with water. They soaked the soap for about three hours and then sprayed the bar of soap with a squeeze bottle full of water. Miranda noticed that when the soap was sitting in the water, it was getting smaller but took a very long time. There was barely a change after the three hours. When they sprayed the bars of soap, they broke down quickly, and bits of soap began breaking off. They repeated the experiment with multiple bars of soap and saw the same results.
What does this data tell you about moving water versus standing water and how it changes the landscape over time?
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. When reviewing the observations and data from Miranda's investigation, one may notice that running water (the spray bottle) eroded more material in a shorter period. When comparing moving water and standing water, there is a significant difference, and running water would change the landscape more quickly.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. When reviewing the observations and data from Miranda's investigation, one may notice that running water (the spray bottle) eroded more material in a shorter period. When comparing moving water and standing water, there is a significant difference, and running water would change the landscape more quickly.
← Didn't Know|Knew It →
Scientists are studying different cliff faces and how their rates of erosion are affected by the slope of the rock formation. DJ thinks that the steeper the cliff, the higher or faster the rate of erosion will be. Matt says it will be the opposite, that the steeper the cliff is, the lower or slower the rate of erosion will be. They know gravity pulls rocks down, and this will have an effect on the cliff's erosion rate. Based on the data chart below, who is correct, and why?
Scientists are studying different cliff faces and how their rates of erosion are affected by the slope of the rock formation. DJ thinks that the steeper the cliff, the higher or faster the rate of erosion will be. Matt says it will be the opposite, that the steeper the cliff is, the lower or slower the rate of erosion will be. They know gravity pulls rocks down, and this will have an effect on the cliff's erosion rate. Based on the data chart below, who is correct, and why?
Tap to reveal answer
DJ and Matt are both on the right track when they are thinking about rocks being pulled down and affected by gravity, but that is where the commonalities stop. DJ is correct in his thinking related to the steep rock cliffs. The steeper the cliff is, the sooner and faster it will be eroded. The steep slope allows the force of gravity to move more rock more quickly. When looking at the data, a trend can be seen, the higher the slope of the cliffside is, the sooner it will erode. A cliffside with a 30o slope will erode in 61 years compared to an 87o slope eroding in 24 years.
DJ and Matt are both on the right track when they are thinking about rocks being pulled down and affected by gravity, but that is where the commonalities stop. DJ is correct in his thinking related to the steep rock cliffs. The steeper the cliff is, the sooner and faster it will be eroded. The steep slope allows the force of gravity to move more rock more quickly. When looking at the data, a trend can be seen, the higher the slope of the cliffside is, the sooner it will erode. A cliffside with a 30o slope will erode in 61 years compared to an 87o slope eroding in 24 years.
← Didn't Know|Knew It →
Scientists are studying different cliff faces and how their rates of erosion are affected by the slope of the rock formation. Meredith wants to come up with a way to extend the amount of time that it takes for a cliff face to be completely eroded. What can Meridith recommend doing after reviewing the relationship between slope and erosion rate in the table below?
Scientists are studying different cliff faces and how their rates of erosion are affected by the slope of the rock formation. Meredith wants to come up with a way to extend the amount of time that it takes for a cliff face to be completely eroded. What can Meridith recommend doing after reviewing the relationship between slope and erosion rate in the table below?
Tap to reveal answer
Meredith can use this data table to look for a pattern or connection between the slope of the cliffside and the average erosion rate. Based on the measurements recorded, the lower the slope, the longer it takes for the cliff to erode. Meredith could suggest building the cliffside up to reduce the slope so that scientists could increase the amount of time it would take to erode. The steep slope allows the force of gravity to move more rock faster, so by reducing the slope, the rock will not move as quickly.
Meredith can use this data table to look for a pattern or connection between the slope of the cliffside and the average erosion rate. Based on the measurements recorded, the lower the slope, the longer it takes for the cliff to erode. Meredith could suggest building the cliffside up to reduce the slope so that scientists could increase the amount of time it would take to erode. The steep slope allows the force of gravity to move more rock faster, so by reducing the slope, the rock will not move as quickly.
← Didn't Know|Knew It →
The data table below shows the width of the beach measured every two years.
What natural process is likely causing the beach to become shorter in width each year?
The data table below shows the width of the beach measured every two years.
What natural process is likely causing the beach to become shorter in width each year?
Tap to reveal answer
The natural process of weathering and erosion happens very slowly. Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. In this example, erosion due to the ocean waves crashing onto the beach is washing away sand, causing it to be slowly moved out to sea, and the beach becomes shorter in width.
The natural process of weathering and erosion happens very slowly. Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. In this example, erosion due to the ocean waves crashing onto the beach is washing away sand, causing it to be slowly moved out to sea, and the beach becomes shorter in width.
← Didn't Know|Knew It →
The data table below shows the width of the beach measured every two years.
Based on the pattern, what will the width of the beach most likely be in year 11?
The data table below shows the width of the beach measured every two years.
Based on the pattern, what will the width of the beach most likely be in year 11?
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. The beach is eroding at a rate of 0.02 meters every two years. It can be predicted that the trend will continue, and in year 11, the beach will be 7.3 meters wide.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. The beach is eroding at a rate of 0.02 meters every two years. It can be predicted that the trend will continue, and in year 11, the beach will be 7.3 meters wide.
← Didn't Know|Knew It →
True or False: The effects of weathering on the rate of erosion cannot be measured.
True or False: The effects of weathering on the rate of erosion cannot be measured.
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. The effects of weathering on the rate of erosion can be measured and often is to determine if reconstruction or human intervention is needed to stop the weathering and erosion in areas.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. The effects of weathering on the rate of erosion can be measured and often is to determine if reconstruction or human intervention is needed to stop the weathering and erosion in areas.
← Didn't Know|Knew It →
Which example is NOT a direct cause of erosion?
Which example is NOT a direct cause of erosion?
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. Wind, water, and gravity can all move bits of broken rock and sediment. Temperature is not a direct cause of erosion. It plays an effect in the freezing and melting of water during the weathering process that breaks rocks apart.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. Wind, water, and gravity can all move bits of broken rock and sediment. Temperature is not a direct cause of erosion. It plays an effect in the freezing and melting of water during the weathering process that breaks rocks apart.
← Didn't Know|Knew It →
What is the best scientific method for determining if erosion is taking place?
What is the best scientific method for determining if erosion is taking place?
Tap to reveal answer
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. Measuring the area over time, taking photographs for comparison, and writing detailed observations are scientific methods for determining if erosion is taking place.
Over time the wind, ice, vegetation, and water wear away small bits and pieces of sediment, rock, and other natural materials. Erosion takes these bits of material and moves them to a new location. Measuring the area over time, taking photographs for comparison, and writing detailed observations are scientific methods for determining if erosion is taking place.
← Didn't Know|Knew It →