257 
Tue Upper Limit oF THE KNOBSTONE IN THE REGION OF BorDEN. By LEE 
H. Jones. 
During the last field season of the Indiana University Geological Sur- 
yey the line of parting between the Lower Carboniferous limestone and 
the Knobstone group was traced through township 1 south, 4, 5, and 
6 east, and 1 north, 4, 5, and 6 east. In this locality there was found 
to be an interesting distribution*ef the knobstone group; and it is with 
this feature that this paper deals. 
In general, the upper limit of the knobstone has a trend of north 
slightly east, keeping within a short distance of the Ohio River from the 
point where it crosses that stream in township 6 south until a point 
five miles west of New Albany is reached. Here it turns to the northeast 
and runs to section 22, 1 south, 6 east, where it turns directly northwest. 
This line is continuous, with but slight deviation to the east or west, 
except in 2 south, 4, 5 and 6 east, where the overlying limestone is entirely 
eut through by the westward-flowing streams, leaving many isolated lime- 
stone areas capping the Knobstone hills. 
From the point where the line of parting between the top of the Knob- 
stone and the overlying Harrodsburg limestone (Lower Carboniferous) 
turns west, in section 22, it runs northwestward in a continuous line until 
it passes west of the headwaters of Muddy Fork of Silver Creek, in town- 
ship 1 south, 5 east, one and one-half miles south of Pekin. 
From this point it runs westward and a little to the south on the south 
side of Blue River, until it reaches section 33, 1 north, 4 east, where it 
passes beneath the drainage level and crosses to the north side of that 
stream. 
Again the line of parting turns to the northeast, and owing to the 
elevation of the rocks in that direction, it is gradually brought back to the 
tops of the hills. At the northeast corner of section 4, township 1 north, 
5 east, it again turns to the west. A glance at the map will readily show 
that the upper limit of the knobstone in the area under discussion forms 
a westward indentation, with its wider part to the east. 
The overlying Harrodsburg limestone in the vicinity of section 22, 
township 1 south, 6 east, is very thin at its eastern and northern edges, 
running out to a feather edge along the line of parting. In this immediate 
locality the line of parting is from one to two miles from the eastern and 
northern face to the knob escarpment; to the west, in section 18, same 
17—ScIENCE. 
