Tales of the Coast
America's Coasts


Glaciated Coastal Variability

Glaciated coasts typically display a greater variety of geomorphic forms than coasts in warmer latitudes. The forms include purely glacial, glacio-fluvial and marine types. Complexity is added by marine reworking of sediments, which can produce barriers, shoals, gravel shores and steep-cliffed shores. Because of the steep slopes of many glaciated coasts, slumping and turbidity flow are major erosive agents. In northern latitudes, the shallow seafloor is gouged by icebergs.

Because glacial ice is studded with rock fragments plucked from the underlying rock, a moving glacier performs like a giant rasp that scours the underlying land surfaces. This process, driven by the great size and weight of the ice sheets, caused enormous erosion and modification to thousands of square kilometers during the Pleistocene epoch.

As a glacier moves, huge amounts of sediment are incorporated into the moving mass. When the ice melts at the glacial front's farthest advance, the sediment load is dropped. Although the major part of the transported material is dumped in the form of a terminal moraine, some sediments are carried further downstream by meltwater streams. The result is a number of distinct geomorphic features such as drumlins, fjords, moraines and outwash plains that may appear along the coast or on the submerged continental shelf.

Glaciated coast
Source: National Oceanic & Atmospheric Adminstration (NOAA)

Glaciated Coastal Variability

Slump: A movement along a curved surface in which the upper part moves vertically downward while the lower part moves outward.

Turbidity Flow: A flowing mass of sediment-laden water.