They cover most of Maine's land surface and include sediments deposited by water, wind, and glacial ice.
Glacial deposits are by far the most abundant surficial materials in Maine.
In addition to the distribution of unconsolidated surficial deposits, the maps also show glacial landforms, directions of glacial ice movement, locations of gravel pits or borrow pits, and other specific features. Information on approximate depth to bedrock and the location of some bedrock exposures is also shown. The map explanation describes the composition of each deposit, its characteristic topography, and its origin. Surficial geologic maps are compiled from field work, well and test hole data, and aerial photograph interpretation. In the field, the geologist examines as many exposures of surficial materials as time and access allow, recording information on the type, thickness, texture, and structure of the sediments exposed.