370 
smaller stream than the present Ohio occupied this territory near Louis- 
ville. It was able to reduce the area of the soft rocks nearly to base-level, 
but it had a much steeper gradient in its graded condition than the much 
larger present Ohio. When the present Ohio invaded the basin of the much 
smaller pre-glacial stream the local peneplain was STATICALLY REJU- 
VENATED, due to the sinking of the larger stream into the piain on ac- 
count of its ability to reach a much lower gradient in its graded condition. 
It may be further noted that the region of the Muscatatuck River to the 
north still possesses such a local base-leveled plain as existed in the New 
Albany locality. It is inferred that the stream which the present Ohio 
dispossessed was somewhat near the size of the Muscatatuck or the 
White river. These streams possess a gradient in their graded condition 
of slightly less than one foot to tle mile, while the Ohio below New Albany 
has a gradient slightly less than three inches per mile. It would appear 
that such a change in gradient initiated by the invading Ohio would allow 
a trenching of something like 90 feet... This corresponds to the amount of 
the trenching of the local peneplain in the vicinity of New Albany. 
Thus the region of soft rocks, the region occupied by the New Albany 
shale and the lower part of the Knobstone group, has been greatly reduced 
as a whole. In this region no remnant of the uplifted Tertiary peneplain 
is preserved. It is low compared to the region on the west where consid- 
erable tracts of the uplifted Tertiary peneplain remain at an elevation of 
900 to 1000 feet above sea level. The broad valley of the Muscatatuck on 
the north is at an elevation of 525 to 550 feet. The Ohio on the south has 
a narrow alluvial plain of about 430 feet in elevation. Low water is 60 
feet lower. Silver creek flowing directly te the Ohio along the strike of 
the outcrop of the non-resistant lower Knobstone shales and the New 
Albany shale has reduced much of its drainage area to a low plain. The 
Museatatuck and its tributaries in the same soft rocks have developed a 
notably wide plain. The continuous lowland developed in these soft rocks 
has been designated the Eastern Lowland by Newsom.’ It will here be 
referred to as the Scottsburg Lowland, from its typical development in the 
vicinity of Scottsburg in Scott County. : 
Immediately to the west of this lowland comes the Knobstone escarpment, 
which from a distant view loses its raged. dissected aspect, and appears 
wall-like to the observer. It rises abruptly 300 to 500 feet above the low- 
land. The short streams which descend the escarpment against the dip of 
the rock have cut down to a fairly low gradient, almost back to their very 
sources. Back of the escarpment the streams often head at the very crest 
and flow west and south down the long back-slope of the cuesta. These 
streams have a relatively long distance to go before reaching the Ohio, 
7This figure is derived by taking the difference between the gradients of the 
Ohio and its assumed predecessor from New Albany to Cannelton, a distance of ap- 
proximately 120 miles. In the latitude of Cannelton valley filling begins to be rather 
conspicuous, and nullifies any difference in the gradients of the former and the pres- 
ent stream, assuming that the valley filling of southwestern Indiana and associated 
regions belongs to the Pleistocene. (See C. A. Malott, The “American Bottoms 
Region”, Ind. Univ. Studies, No. 40, 1919, pp. 26-34.) 
8J. F. Newsom, A Geological Section Across Southern Indiana from Hanover to 
Vincennes, Proceedings of the Indiana Academy of Science, 1897, p. 251. 
