

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



No. 18. 



REPORT 



OF THE 



GEOLOGICAL EXPLORATION OF THE FORTIETH PARALLEL 



MADE 



BY OEDEE OF THE SECEETAEY OF WAE ACCOEDING TO ACTS OF 

 CONGRESS OF MAECH 2, 1867, AND MAECH 3, 1869, 



UNDER THE DIRECTION OF 



BRIG. AND BVT. lAJOR GENERAL A. A. HUMPHREYS, 



CHIEF OF ENGINEERS, 



BY 



CLARENCE KING, 



U. S. GEOLOGIST. 



I-II 



