Eventually rock flour settles, sometimes forming thick deposits. Deposits of glacial flour in the geologic record help glacial geologists create a picture of past environments. The presence of this material in Maine indicates that this region once was below sea level and that glaciers were near-by, releasing their material to the environment. If the glacier reaches a body of water and part of the glacier floats as an ice tongue or an ice shelf, some of the material close to the grounding line will slowly melt out and drop through the water to the seafloor. There is also a way for ice-rafted debris to be carried over a huge distance.
Icebergs can break off, or calve, from the outlet and valley glaciers .
These bergs can float across the Southern Ocean and beyond, slowly melting and dropping their glacial material a great distance from the original glacier. An iceberg containing glacial debris. This berg will travel in the ocean, slowly releasing its material to the sea floor. Ice-rafted debris in the sediment record is one way that glacial geologists trace the history of ice on the continents. Lots of ice-rafted debris in the ancient sediment record from Antarctica means large ice sheets existed.