j74 
flow westward and southward, that the divide is being shifted down the 
dip of the rock westward and southward. This condition of instability 
of the position of the crest of the escarpment has been continued from the 
past. From early topographic maturity until the beginning of old age 
is a period of drainage adjustment. When adjustment has been completed, 
old age of the stream system has already begun. In the region in question 
stream adjustment began a long time ago, but the adjustment is far from 
complete. 
Since the short, steep-headed streams coming down from the Knobstone 
escarpment have a decided advantage over the back-slope streams, they 
have a tendency to develop their drainage area by headward erosion into 
the territory drained by the back-slope streams. The headwaters of the 
backslope streams may be expected to be captured by the eastward and 
northward flowing streams. Search along the escarpment shows that this 
drainage adjustment as a whole has not taken place, but in a number of 
places appears imminent. There is one place, however, where such piracy 
has notably taken place. This is along the line of Muddy Fork of Silver 
Creek, from near Pekin in southeastern Washington County to near 
Broom Hill in Clark County. Here, much reversal of drainage has already 
taken place, and a great break occurs in the escarpment along the line of 
this stream. Newsom” repeatedly calls attention to this rather unusual 
opening in the Knobstone escarpment. His maps show a beautiful example 
of barbed drainage pattern and the broad col at Pekin where the formerly 
westwardly flowing stream entered Muddy Fork of Blue River But it does 
not appear that Newsom realized the significance of these tell-tale features. 
Ashley" calls attention to the area and the causes of the condition in the 
following words: ‘“—the soft and easily eroded nature of the Knobstone 
has allowed the erosion to proceed more rapidly so that the gorge has in 
many cases sunk its bottom down to drainage level, and the point of rapid 
descent has advanced from the mouth to the headwaters on account of 
the shortness of the stream. Indeed, in many Gases it is evident that, due 
to their shortness, these northward and eastward flowing streams are cut- 
ting down the divides at the expense of the streams flowing the other way. 
A good illustration of this ‘river stealing’, as it is called, is seen about 
Borden. The valley in which Borden lies originally drained to the north- 
west, the divide being nearly as far east as Broom Hill. But the Muddy 
Fork of Silver Creek, having cut down its side of the divide faster than 
the stream draining to the northwest, has captured all the drainage about 
Borden and it is only a question of time when it will extend up so far as 
to tap the Mutton (Muddy) Fork of Blue River at Pekin and divert all 
the drainage above that point to Silver Creek”. 
The topographic map accompanying this paper shows the topographic 
conditions of a small area in the region of Pekin and Borden. This some- 
what restricted region offers details of much interest in the Gratnage 
J. F. Newsom, Geologic and Topographie Section Across Southern Indiana, 26th 
Ann. Rept. Ind. Dept. Geol. & Naturai Resources, 1901. 
UGeology of the Lower Carboniferous Area of Southern Indiana, 27th Annual 
Report of the Dept. of Geology and Natural Resources, 1902, p. 61. 
