Most us beaches are shrinking or encroaching on the

29.
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 not a
likely cause:
A) Dams have increased sediment transport from the land to the sea.
B) Global sea level is rising, covering more land.
C) Levees along rivers have blocked sediment supply to deltas that feed longshore drift, forcing
the sediment to fall in deep water where waves cannot pick it up.
D) Water, oil and gas are being pumped out of the ground in some places, causing subsidence.
E) Sea-level rise as the last ice age ended flooded river valleys to form bays, and sediment now
is deposited in these bays rather than being delivered to beaches.
30.
You are flying along the coast, and you observe a sort of dam or wall, called a groin, sticking out
from the coast. Sediment has piled up on one side of the groin, with erosion on the other side.
You can reasonably infer that:

31.
Sandy beaches: