Rivers as Agent of Change
While rivers are important natural resources for humans, they can also be incredibly destructive. Whether the nature of their destruction os slow and steady over thousands of years or a single, catastrophic flood that fundamentally changes the landscape and perhaps even erases a city or kills thousands of people, rivers have incredible power to shape the landscapes they flow through.
First, log into BbLearn and complete 'Assignment 4.8: Fluvial Processes' to better understand how fluvial systems shape landscapes.
Below are several example of landscapes shaped by the power of rivers. For each landscape, form a hypothesis based on your reading of what processes may have shaped the landscape shown. Think about and try to answer the following questions:
1. Does the landscape have sharp relief -- meaning, are there topographical features like cliffs, canyons, or coulees or is the terrain more gradual and undulating? Both of these types of relief can be produced by rivers, but sharp relief is often found associated with a powerful river or flood event.
2. What kind of soils can you see? Deep, loamy, rich soils are often associated with river floodplains, while clay or sandy soils are rare in these areas. When you can't see the soils (like in the pictures) you can make a guess at what is there by the surface vegetation. It is agriculture (which requires good loamy soils) or sparse brush (usually indicative of sandy soils)? If the soils in the river plain are gravelly, this is often a sign of a fast-running, younger river.
3. Look at the river bed itself -- do you see features that indicate this is a river prone to large flood events (like huge boulders that could only have been moved during a flood)? How high are the river banks?
4. How have humans dealt with the river and its landscape? Have they built dams or levees? Have they straightened the river channel or let it course naturally?
First, log into BbLearn and complete 'Assignment 4.8: Fluvial Processes' to better understand how fluvial systems shape landscapes.
Below are several example of landscapes shaped by the power of rivers. For each landscape, form a hypothesis based on your reading of what processes may have shaped the landscape shown. Think about and try to answer the following questions:
1. Does the landscape have sharp relief -- meaning, are there topographical features like cliffs, canyons, or coulees or is the terrain more gradual and undulating? Both of these types of relief can be produced by rivers, but sharp relief is often found associated with a powerful river or flood event.
2. What kind of soils can you see? Deep, loamy, rich soils are often associated with river floodplains, while clay or sandy soils are rare in these areas. When you can't see the soils (like in the pictures) you can make a guess at what is there by the surface vegetation. It is agriculture (which requires good loamy soils) or sparse brush (usually indicative of sandy soils)? If the soils in the river plain are gravelly, this is often a sign of a fast-running, younger river.
3. Look at the river bed itself -- do you see features that indicate this is a river prone to large flood events (like huge boulders that could only have been moved during a flood)? How high are the river banks?
4. How have humans dealt with the river and its landscape? Have they built dams or levees? Have they straightened the river channel or let it course naturally?
What hypotheses did you develop? There are several animations in the textbook resource support website that describe these process and show how they work in greater detail.