A city or farmer needs a new water supply. Where can suitable water-bearing formations be found? A new limestone quarry is considered. Where are the most suitable limestone deposits? A coal mine is being planned. How deep must a shaft be sunk to reach the nearest minable coal and what will the mining conditions be? A land owner has a clay deposit on his land. What uses can be made of it? A road is to be constructed. Are sand and gravel or limestone deposits available nearby for construction materials? A farmer wants to know whether there might be oil on his property. Are oil-bearing structures present and, if so, at what depth? These are typical questions brought to the Illinois State Geological Survey by the industries and people of Illinois. From its accumulated store of information and experience, the Survey provides answers. This storehouse of knowledge is the result of the Survey’s continuous program of geologic exploration, mapping, research, and organization and interpretation of data. The Survey explores and maps the geology and mineral resources of the state, does research to find new and improved uses for our mineral resources, and organizes and interprets basic geologic information gathered from well logs, rock samples, and field studies, putting them all into usable form. Such knowledge is shared with the public through publications, maps, lectures, and personal consultations with industries, drillers, engineers, land owners, teachers, and others in need of geologic information. The discovery of facts about the rich mineral resources of Illinois has, in effect, only begun, and it is the task of the Geological Survey to continue to collect and apply new information so that our resources can be used to the best advantage. EDUCATIONAL EXTENSION PROGRAM The Educational Extension Section of the Geological Survey conducts six field trips each year, in various parts of the state, for teachers, students, and laymen. It also assembles and distributes rock and mineral collections for Illinois educational groups, gives lectures, prepares exhibits, and identifies rocks and minerals for the public. Educational Extension publications, such as this book, are simplified discussions of geological subjects. Available for 25 cents each, these include: Educational Series 4: Guide for Beginning Fossil Hunters, by Charles W. Collinson. Educational Series 5: Guide to Rocks and Minerals of Illinois. Educational Series 6: Field Book of Pennsylvanian Plant Fossils of Illinois, by Charles Collinson and Romayne Skartvedt. Many technical discussions of the various phases of Illinois geology also are published by the Geological Survey. Regional reports on the geology and mineral resources of some areas are available in many school and public libraries or they may be purchased from the Survey. Some of the regional reports include: