Question

EXERCISE 13.7 Deducing the History of the Susquehanna River Name: Course: Section: Date: (a) What is unusual about the relationship between the Susquehanna and Juniata rivers and the valley-and-ridge topography shown in Figure 13.202 Most of the small streams flow in the elongate valleys, but the Susquehanna and its tributary, the Juniata River, cut across the ridges at nearly right angles. It is tempting to think that the big streams had enough energy to cut through the ridges, whereas the small ones didn't, but that is not the case. The answer lies in a multistage history of which only the last stage is visible today (b) Why do most of the smaller streams flow in the elongate valleys? (C) Suprest as many hypotheses as you can to explain why the two larger rivers cut across the valley-and-ridge topography Hint: How might the landscape have been different at an earlier time? Rivers with enough energy to cut through the ridges should certainly have been able to simply meander around them, but the Susquehanna and Juniata rivers didn't take the easy way out. It's almost as if they didn't even know the ridges and valleys were there (d) With that clue, suggest a series of events that explains the behavior of the Susquehanna and Juniata rivers. Hint: This type of stream is called a superposed stream.

Answer 1

A. Susquehanna and Juniata river meets at Duncannon area, and it cuts a ridge system and makes a ridge gap which is very unusual because when a river meets a ridge system it courses become diverted and run parallel to the ridge.

B. In the question, there is a hint that small streams cannot cut the ridge dut it's less energy and it also says that is not the proper reason because we see the last stage in the history.

The other possible reason is there may be a system of faults parallel to the ridge, which causes the river(stream) flow through it (fault).