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A) There is no sand here, so this must be a place where sand is not produced.B) There is no sand here, so sand must be lost to deep water fast enough in comparison to sand supply that sandy beaches have not formed.C) There is no sand here, because Acadia and the surrounding coast of Maine get huge storms, and sandy beaches cannot exist where such huge storms occur.D) There is no sand here, because the Park Service mines the sand to pave park roads.E) There is sand under the rocks; the Park Service places the rocks on top to protect the beach, and takes the rocks off on sunny days.
Feedback: Granite does weather to make sand, so some sand must be produced, but this is not a sand deposit, so sand loss must be fast enough to prevent large accumulations. The Park Service neither mines sand from beaches, nor hides sand on beaches. And huge storms hit Florida and the Gulf Coast, but they have sandy beaches.Points Earned: 1.0/1.0 Correct Answer(s):B5. In the picture above, the yellow arrow points at a jetty, a sort of sea wall or groin or dam, that was constructed along the coast of Washington. A likely interpretation of what you see here is:A) Sediment transport is typically from the upper left, and the sediment falls into the lee of the jetty on the right and piles up, while the left side is unaffectedB) Sediment transport is typically from the right, causing deposition to the right of the jetty but no change to the leftC) Sediment transport is typically from the right, causing deposition to the right of the jetty but erosionto the leftD) Sediment transport is typically from the upper left, and the sediment falls into the lee of the jetty on the right and piles up, while erosion happens on the leftE) Sediment transport is typically directly from the ocean to the land, piling up sediment on both sides
of the jetty.Feedback: A jetty works like a dam, trapping sediment on the “upstream” side and letting clean water pass to the other side, where the clean water erodes. So, the transport is typically from the right. A large beach has been formed there, but erosion “downstream” is cutting around the end of the jetty.Points Earned: 1.0/1.0 Correct Answer(s):C1. Most U.S. beaches are shrinking or encroaching on the land rather than growing or moving seaward, so the land of the U.S. is getting smaller, not bigger. Which of the following is a likely cause for loss of at least some of our beaches:A) Land is sinking in some places as it recovers from being bulged up beyond the edge of the ice-age ice sheets.B) Global sea level is falling, exposing more land.C) Dams have greatly increased the sediment supply to deltas that feed longshore drift to grow beaches.D) Water, oil and gas are being pumped into the ground in some places, causing the land to rise.