how might have barrier islands been built? a. barrier island could be caused by
ID: 235912 • Letter: H
Question
how might have barrier islands been built?
a. barrier island could be caused by excessuve flow of streams a few thousand years ago. the excess of sediment was carried by offshore currents to create the barrier islands.
b. the could have been produced by reef animals. With the emergence of the coastline they have become barrier islands
c. they may have been costal dunes during the last ice age. wuth the melting of the ice and rise in sea level, the dunes became the barrier island.
d. the barrier islands may have been formed a few million years ago when the climate was warmer. The warmer climate allowed the growth of many near shore plants like mangroves. these plants trapped much sediment to create the island.
Explanation / Answer
C: A barrier island is an elongated offshore ridge of sand running parallel with a mainland coast and separated from it for almost its entire length by a lagoon. They range in size from a few meters in width and hundereds of meters long to upto 1 km in width to hundreds of kilometers long. They are especially found in gently sloping coasts as well as low tidal range. In Atlantic and Gulf of Mexico coasts of USA they are commonly found. Tidal inlets are found at intervals along the barrier.
Barrier islands initially developed above sea level on beach ridges and coastal dunes and as sea level rose in Holocene due to flooding and lagoon formation they were separated from the mainland. So the statement C they might have been coastal dunes during the last ice age, with the melting of the ice and rise in sea level, the dunes become barrier island is correct
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