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1 foot. B.10 feet. C.0.1 feet. D.0.001 feet. E.In central Pennsylvania, a typical rainfall supplies about an inch of water, or just under 0.1 foot. 30 feet of rain would be a big storm every day, about equal to the wettest place on Earth, and while sometimes it may seem our rain never ends, we really do have clear days. 0.3 feet is a mere 3 or 4 rainfalls per year, and really is a dry desert. 0.03 feet would be the driest place on Earth, and 0.003 doesn’t occur on Earth. 3 feet is a nice number for central Pennsylvania. 1/3 of that is 1 foot/year, and is about the cutoff for defining a desert. (People often use 10 inches of rain per year, rather than a foot, but that’s close enough.) Points Earned:1/1 Correct Answer:B Your Response:B Some of the water that falls as rain or that melts from snow in central Pennsylvania each year is evaporated, especially from trees, and goes back to the sky, but some water does not evaporate. What happens to most of that remaining water? 2.Most of it flows directly over the surface to streams. A.Most of it is used in Pepsi bottling plants. B.Most of it is stored in caves to fill them up. C.Most of it soaks into the ground and then flows through the ground to streams. D.Most of it falls directly on streams and lakes. E.Points Earned:1/1 Correct Answer:D Your Response:D A dam is built on a river, forming a reservoir. Over time, this likely will cause: 3.Nothing to happen; dams don’t matter to upstream or downstream conditions. A.Ohio State students to take a leak in a sinkhole behind the Nittany Mall. B.Rapid erosion of sand upstream of the reservoir, and downstream of the dam. C.Sedimentation to bury farmer’s fields upstream of the reservoir, and sedimentation of sand downstream of the dam. D.Sedimentation to bury farmer’s fields upstream of the reservoir, and erosion of sand downstream of the dam. E.The stream will slow where it enters the new lake, and so will deposit sediment to form a delta rather than cutting downward or having no change. As the delta builds out into the lake, the upstream end of the delta must build up so that the stream still slopes downward, and this will tend to bury fields upstream. Meanwhile, moving water can carry sediment. Sediment-free water is released from a dam but often later observed to have sediment, so erosion must be occurring. Loss of sand bars below the Glen Canyon Dam shows that sand is carried away downstream of dams. Dams stops floods that are needed to move the big pieces (boulders, cobbles), and dams cause sedimentation upstream, but not downstream. Our friends from Columbus are probably too cultured to be relieving themselves outside the Mall; besides, the last time I looked during a visit from the Buckeyes, the inebriated people were not straying that far away from the downtown bars.
Points Earned:0/1 Correct Answer:E Your Response:C When we speak of the Mississippi Delta, most people mean some interesting region in Louisiana with good music and seafood. Geologically, however, the Mississippi Delta is: 4.