THE NATURAL HISTORY SURVEY 



The Board of Managers of the Natural History Survey 

 take pleasure in presenting the fifth of its proposed publica- 

 tions. It is the third report of those relating to the geological 

 features of the area and is devoted to the mineralogy of 

 Chicago and vicinity. 



The area covered by the survey is made to include the 

 first great moraine which sweeps around the head of Lake 

 Michigan, as well as several weak morainic lines lying nearer 

 the lake. It also includes the ancient beaches of Northeastern 

 Illinois and a portion of the outlet of the body of water which 

 formed them. It is a country exceptionally full of varied and 

 interesting features. 



This territory is about forty-eight or fifty miles square, 

 which after deducting the approximate area of the lake- 

 covered portions, leaves nearly eighteen hundred square miles 

 of land surface. It comprises all of Cook and Du Page Coun- 

 ties, the nine north townships of Will County and a portion of 

 Lake County, Indiana. 



While it is not a locality notable for its mineral resources, 

 yet quite a variety of beautiful and economic forms are ob- 

 tained which are of sufficient scientific value to warrant the 

 publication of a report devoted to them. 



Some of the species are emigrants and only found in the 

 drift, yet students of mineralogy will doubtless note with 

 interest the large number recorded and also that nearly all the 

 mineral classes are represented. 



This report has been prepared by Dr. Alja Robinson 

 Crook, Professor of Mineralogy, Northwestern University, and 

 represents several years of careful study and field work. 



