Surficial deposits and materials in the eastern and central United States (east of 102 degrees west longitude)

The surficial geologic map of the Eastern and Central United States depicts the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the "ground" on which we walk, the "dirt" in which we dig foundations, and the “soil” in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The map is based on 31 published maps in the U.S. Geological Survey's Quaternary Geologic Atlas of the United States map series (U.S. Geological Survey Miscellaneous Investigations Series I-1420). It was 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.
This map is not a map of soils as recognized and classified in agriculture. Rather, it is a generalized map of soils as recognized in engineering geology, or of substrata or parent materials in which agricultural, agronomic, or pedologic soils are formed. Where surficial deposits or materials are thick, agricultural soils are developed only in the upper part of the engineering soils. Where they are very thin, agricultural soils are developed through the entire thickness of a surficial deposit or material.
The surficial geologic map provides a broad overview of the areal distribution of surficial deposits and materials. It identifies and depicts more than 150 types of deposits and materials. In general, the map units are divided into two major categories, surface deposits and residual materials. Surface deposits are materials that accumulated or were emplaced after component particles were transported by ice, water, wind, or gravity. The glacial sediments that cover the surface in much of the northern United States east of the Rocky Mountains are in this category, as are the gravel, sand, silt, and clay that were deposited in past and present streams, lakes, and oceans. In contrast, residual materials formed in place, without significant transport of component particles by ice, water, wind, or gravity. They are products of modification or alteration of pre-existing surficial deposits, surficial materials, or bedrock. For example, intense weathering of solid rock, or even stream deposits, by chemical processes may produce a residual surficial material that is greatly transformed from its original physical and chemical state.
In recent years, surficial deposits and materials have become the focus of much interest by scientists, environmentalists, governmental agencies, and the general public. They are the foundations of ecosystems, the materials that support plant growth and animal habitat, and the materials through which travels much of the water required for our agriculture, our industry, and our general well being. They also are materials that easily can become contaminated by pesticides, fertilizers, and toxic wastes. In this context, the value of the surficial geologic map is evident
The map and its digital database provide information about four major aspects of the surficial materials, through description of more than 150 types of materials and depiction of their areal distribution. The map unit descriptions provide information about (1) genesis (processes of origin) or environments of deposition (for example, deposits related to glaciation (glacial deposits), flowing water (alluvial deposits), lakes (lacustrine deposits), wind (eolian deposits), or gravity (mass-movement deposits)), (2) age (for example, how long ago the deposits accumulated or were emplaced or how long specific processes have been acting on the materials), (3) properties (the chemical, physical, and mechanical or engineering characteristics of the materials), and (4) thickness or depth to underlying deposits or materials or to bedrock. This approach provides information appropriate for a broad user base. The map is useful to national, state, and other governmental agencies, to engineering and construction companies, to environmental organizations and consultants, to academic scientists and institutions, and to the layman who merely wishes to learn more about the materials that conceal the bedrock. The map can facilitate regional and national overviews of (1) geologic hazards, including areas of swelling clay and areas of landslide deposits and landslide-prone materials, (2) natural resources, including aggregate for concrete and road building, peat, clay, and shallow sources for groundwater, and (3) areas of special environmental concern, including areas of intense erosion and areas of potential contamination of soil and groundwater.
The map also includes lines depicting the maximum limits of glacial advance during selected time periods.

ussurfm020 - Map units, as polygons, geographic projection
glacal020  - Glacial limits, as lines without line decorations, geographic projection
ussurflam  - Map units, as polygons, Lambert_Azimuthal projection
glaciallam - Glacial limits, as lines without line decorations, Lambert_Azimuthal projection

surfpoly.shp - Map units, as polygons, geographic projection
surfarc.shp  - Attributed contacts and boundaries
glacline.shp - glacial limits, as lines