Read Online The Geological Map of Illinois (Classic Reprint) - Stuart Weller file in PDF Online

Excerpt from The Geological Map of IllinoisPurpose of a geological map - The position of the natural eco nomic products which exist within the crust Of the earth in any region, is determined either by reason of the physical conditions pres ent at the time Of formation Of the rocks in which they are contained, or by reason Of subsequent dynamic changes. Thus beds Of coal