Map of surficial deposits and materials in the eastern and central United States (east of 102 degrees West longitude)

This data set contains surficial geologic units in the Eastern and Central
United States, as well as a glacial limit line showing the position of
maximum glacial advance during various geologic time periods. The
geologic units represent surficial deposits and other surface materials
that accumulated or formed during the past 2+ million years, such as
soils, alluvium, and glacial deposits. These surface materials are
referred to collectively by many geologists as regolith, the mantle of
fragmented and generally unconsolidated material that overlies the bedrock
foundation of a continent.

This data set and the printed map produced from it, U.S. Geological Survey
(USGS) Geologic Investigation Series I-2789, were based on 31 published
maps in the USGS's Quaternary Geologic Atlas of the United States map
series (USGS Miscellaneous Investigations Series I-1420). The data were
compiled at 1:1,000,000 scale, to be viewed as a digital map at
1:2,000,000 nominal scale and to be printed as a conventional paper map at
1:2,500,000 scale.