Lake and Porter Counties are subdivided into three physiographically and geologically distinct regions: (1) the Calumet Lacustrine Plain, (2) the ValparaisoMorainal Area, and (3) the Kankakee Outwash and Lacustrine Plain. The surficial deposits of these regions, which range in thickness from 40 feet near the Kankakee River to more than 250 feet near Valparaiso, Ind,. Are the products, either directly or indirectly, of the Wisconsinan Age of glaciation. The Calumet lake plain is characterized by low-lying complexly intermixed clay, sand, and silt deposits, mostly of glacial Lake Chicago origin , The Valparaiso Moraine forms high ground in the two counties and is composed of clay-rich to fine sandy till. Sand and fine gravel deposits constitute the bulk of the Kankakee Outwash and Lacustrine Plain, this area being the low-lying outwash and flood plain for the glacially derived rivers as well as for the present Kankakee River. The two-county area has an abundance of geologic and geologically related resources; some of the most important are: (1) groundwater of the Kankakee Outwash and Lacustrine Plain and Valparaiso Morainal Area, (2) sand deposits of glacial Lake Chicago and of recent origin, (3) rich soils developed on the Valparaiso Moraine and Kankakee outwash plain, and (4) surface water in the form of streams, rivers, and small lakes. Some of these resources have already been damaged during the course of man’s habitation and use, but all can, with proper understanding of the problems and the willingness to act, be saved from further unnecessary degradation. Certain kinds of land use, which are partly dependent on the local geology, are potential sources of difficulty. These include (1) siting and use of sanitary landfills, (2) placement of septic systems, sewage lagoons, and industrial holding ponds, (3) management of flood plains, (4) development of the Lake Michigan shoreline, (5) construction of all kinds in areas where little is known about the engineering and hydrologic properties of the materials, (6) disposal of industrial wastes by deep well injection methods, and (7) development of groundwater supplies without sufficient hydrologic and geologic data. The environmental problems of Lake and Porter Counties, are related to geology, are as varied and complex as the materials themselves. Specific questions related to a given problem are best answered by the competent consultant equipped to do so. This report, though intended to supply valuable geologic information on a variety of land use related subjects, should not replace onsite evaluation of the salient parameters involved with each problem that potentially arises whenever man uses earth materials or otherwise disturbs or rearranges the natural earth condition.