266 
Figures 2 and 3 show an unconformity. These figures, however, are 
in part ideal, as the actual line of contact, or unconformity (if such it is), 
was not observed, being covered with debris. It is not possible, from the 
data in hand, to say surely whether this strip of limestone owes its ex- 
istence to an unconformity or a fault. 
The peculiar distribution of this strip of limestone effects the topog- 
raphy of that section of the country in which it is found. West of the 
easternmost line of contact the country is rolling, with quite a number of 
sink holes, characteristic of limestone formations. East of that line of 
contact the country is very rough; the streams are in deep, narrow rayines 
characteristic of the knobstone area. 
The present location of the streams running north and south near this 
point is uue largely to the unconformity, they following the line of contact, ~ 
or, haying cut below the limestone level, are following channels in the 
knobstone. 
An Oxtp River CHANNEL IN SPENCER County, INDIANA. By ARTHUR 
C. VEATCH. 
All that portion of Spencer County south of the line which separates 
townships 5 south from that of 6 south, and west of a line running north 
and south through Grandview, may be divided into two physiographic 
regions, a plain and a hill region. 
The plain may be subdivided into three parts. First, a broad, level 
plain extending southwest along the western boundary of the county. (See 
Fig 1.) It has the same general trend as Little Pigeon Creek, and will 
therefore be called Pigeon Plain, although it is not now occupied by Little 
Pigeon Creek. The two valleys are separate and distinct. Where Pigeon 
Plain enters the northern part of the area under consideration it is about 
two miles wide. It gradually widens until at Midway it is about four 
miles, at Richland five, and continues at this width until it enters the 
second division of the plain region, the river plain of the present Ohio. 
Only a portion of this river plain comes properly under the present dis- 
cussion of Spencer county, as a part lies in Kentucky. Taking the two 
parts together, the average width of the plain is between four and five 
miles. That portion which lies in Indiana is very irregular on account of 
the meandering course of the river. It includes all land locally termed the 
