PROFESSIONAL PAPERS OF THE ENGINEER DEPARTMENT, U. S. ARMY. 



]S"o. 18. 



IlEI>ORT 



GEOLOGICAL EXPLORATION OF THE FORTIETH PARALLEI; 



BY OEDEE OF THE SECEETAEY OP WAE ACCOEDING TO ACTS OF 

 CONGEESS OF MAECH 2, 1867, AND MAEOH 3, 1869, 



inSTDEE THE DIRECTION 01' 



BRIG. ANB BVT. MAJOR GENERAL A. A HUMPHREYS, 



CHIEF OF ENGDfEEBS, 



BT 



CLARENCE KING, 



u. B. GEOLOGIST. 



:^ 



A' 



