STATE OF ILLINOIS 



HON. DWIGHT H. GREEN, Governor 



DEPARTMENT OF REGISTRATION AND EDUCATION 



HON. FRANK G. THOMPSON, Director 



BOARD OF NATURAL RESOURCES AND CONSERVATION 



HON. FRANK G. THOMPSON, Chairman 

 EDSON S. BASTIN, Ph.D., D.Sc, Geology 

 ROGER ADAMS, Ph.D., D.Sc, Chemistry 

 LOUIS R. HOWSON, C.E., Engineering 

 WILLIAM TRELEASE, D.Sc, LL.D., Biology 

 EZRA JACOB KRAUS, Ph.D., D.Sc, Forestry 

 ARTHUR CUTTS WILLARD, D.Engr., LL.D 

 President of the University of Illinois 



GEOLOGICAL SURVEY DIVISION 



M. M. LEIGHTON, Chief 



mmnumJ^, i^f ,9'-°G'CAL SURVEY 



3 3051 00005 7517 



