Stream Dynamics
What would likely happen to the meander between placemarks F and G if a brief flood were to occur?
Water would overflow the river channel and flow across the floodplain. This would scour new channels that would cut off the meander between placemarks F and G.
The gradient, or slope, of a riverbed is found by dividing the change in elevation between two points on the river in meters by the distance between the two points in kilometers. What is the gradient of the stream channel between placemarks A and B? (Answer to the nearest 10 meters per kilometer.)
100 meters per kilometer
What is the length of the channel between placemarks A and B?
7.0 kilometers
Calculate the difference in elevation between placemarks A and B. (Answer to the nearest 10 meters.)
720 meters
Which answer best explains why the sediment deposited by the Roaring River at placemark B is significantly coarser than the sediment deposited at placemark C?
A sudden change in river gradient caused the water to flow more slowly. As the water slowed down, its ability to carry materials, and more specifically the size of the particles the water could carry, decreased. So as the water slowed, first the larger and then the finer particles were deposited.
Which answer best describes the effects of the sediment deposition at placemark E on the Fall River?
The Fall River has been partially dammed by sediment contributed by the Roaring River. Just downstream (east) of the alluvial fan, the channel is straighter than it is upstream (west) and near the fan. The partial damming has rerouted the upstream Fall River channel around depositional debris. Submit
What evidence best supports the argument that the sediments at placemark C were deposited before those at placemark E?
The present-day Roaring River channel flows approximately 30 meters north of placemark E. There are several "fossil channels" visible near placemark C, which are currently dry and covered in vegetation.
What kinds of sediments seem to have been deposited at this location? Which of the following statements best characterizes these sediments compared to the material at placemark B? There are numerous photos of each area that have been provided by other users. Although there are not photos right at placemark C, checking out nearby photos will help you evaluate sediment sizes for each area.
The sediments at placemark C are much finer than those at placemark B. Submit
Where in the meanders do point bars and cut banks occur, and how do they differ in appearance?
Point bars, which are light-colored in the imagery, occur on the inside of meanders, whereas cut banks, which are darker in color, occur on the outside of meanders.
