I 
PROFESSIONAL PAPERS OP THE ENGINEER DEPARTMENT, U. S. ARMY. 
No. 18. 
OF THE 
GEOLOGICAL EXPLORATION OF THE FORTIETH PARALLEL 
MADE 
BY OEDER OF THE SECRETARY OF WAR ACCORDING TO ACTS OF 
CONGRESS OF MARCH 2, 1867, AND MARCH 3, 1869, 
UNDER THE DIRECTION OF 
BRIG. AND BVT. MAJOR GENERAL A. A HUMPffREYS, 
CHIEF OF ENGINEERS, 
BY 
CLARENCE KJM, 
U. S. OEOLOGIST. 
