Calving Glaciers

These two short video clips show the front of a glacier "calving" into the water. This is one of the methods by which glaciers deposit their material carried down from the mountains. Glaciers collect rock debris from adjacent slopes as well as from plucking the rock from beneath the glacier. The rocks that collect on or in the glacier will drop out when the glacier melts.  If this happens in a body of water the rocks will drop into a muddy bottom as a dropstone. Compare the video with the simple animation.  These glaciers are in Alaska. During the Precambrian, Utah could have looked much the same.

(Videos courtesy of NASA-GSC)