Based on what you see in the photo below, how do medial moraines form? (2 pts) 7

Question

Based on what you see in the photo below, how do medial moraines form? (2 pts) 7. 8. The photo below shows a meltwater stream from an Alaskan glacier. The water is flowing from left to right. What two stream channel types are present, and what is a possible explanation for why the channel type changes at the point indicated by the arrow? (Hint: Think back to Chapter 9, specifically the characteristics of braided streams.) Stream channel types: Explanation for why the channel type changes: (3 pts) and (2 pts)

Explanation / Answer

7) Medial moraines are the glacially deposited geomorphic features which are formed when the debris of the two lateral moraines meet at a single intersection point towards the direction of the glacial movement. They direction of the medial moraines are always parallel to that of the direction of movement of the glacier. In the given figure, the point at which the two lateral moraines meet, is the point where the formation of the medial moraine initiated with the accumulation of the debris collected by the lateral moraines.

8) Since it is given that the river channel is orginating from the Alaskan glacier, therefore the gradient of the river is too high and hence the sediment carried along with the river is also high in amount. Now if we consider a braided river channel, the gradiet of the river should be very high and the erodibility of the river due to the gradient is also very high.

Hence from the stream channels it can be said that the channel types are (to the left) braided river and (to the right) meandering river channels. The justification to the naming is quite obvious that the sinousity of the channel is increased towards the right of the channel.

The channel type changes may be because of the change in the gradient of the river and the amount of the sediment in the river. The change in these parameters causes the change in the direction of the erosion from the front side in the braided system to that of the lateral sides in the case of the meandering systems.

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