Terrace Deposits of the Monoiujahela River. — White, 'ill 
sylvaniais new. The resultant modifications which such a 
change of direction in a great river system must necessarily 
bring to pre-existing drainage lines, are so varied and amaz- 
ing even in contemplation, that their study must furnish many 
problems of surpassing interest to topographers of the modern 
school, so ably typified by Prof. Davis and his work. 
he following table represents the descent of the ancient 
Monongahela river toward the lake region for a portion of its 
course between Weston, W. Va., and Sharon, Pa., as well as 
the present water levels between the same points, and also the 
highest levels of the Morgantown beds, where known: 
Present Ancient Top of 
Miles river, river, Deposits, 
A. T. A. T. A. T. 
Weston 990 1,000 1,030 
40 Clarksburg 916 986 1,020 
75 Fairmont 851 973 1,067 
101 Morgantown 787 916 1,038 
117 Geneva 772 912 1,022 
206 Pittsburg 700 890 990 
332 Ptochester 662 865 
237 Beaver Falls 715 860 
246 Rock Point 740 840 
257 New Castle 780 825 
278 Sharon 840 780 
This table shows that while the present river falls 290 feet 
between Weston and Pittsburg, the floor of the ancient sti-eam 
descended only 110 betwen the same points, or only about one- 
half foot per mile, which is practically that of a base-leveled 
valley, or one quite advanced in age, to say the least. The 
rapid descent of the modern river below the old rock floor of 
the ancient one gives rise to the steep slopes and gorge-like 
character of the Monongahela valle}'^ everywhere between Wes- 
ton and Pittsburg, while the same is true of the lower courses 
of all the larger tributary streams, the descent in these being 
very rapid in the last few miles of their courses, while in their 
upper reaches the slope is gentle and the topography much 
older looking. 
The smaller streams, which rise only five to ten miles back 
from the Monongahela, descend to it in the last mile or two of 
their courses by a series of rapids and cascjides, while the still 
smaller brooks and rivulets have cut more notches in the 
bounding valley walls below the level of the ancient rock floor 
