Richmond Group of Ciiiciiiiiati Anticline. — Focrstc. 357 
Western Ohio and eastern Indiana appear co have been an 
area of long continued progressive depression during the de- 
position of the entire Cincinnati series. Evidences of shal- 
low water conditions are found at all levels within this series. 
The numerous borings for gas and oil in western Ohio* 
have shown that the Cincinnati series reaches its greatest 
thickness in the most eastern wells, along a line extending be- 
tween Fayette and Ottawa counties. Conditions east of ti.ese 
counties are unknown. From the line which joins the most 
eastern wells, westward, the thickness diminishes everywhere. 
The wells in Indiana! show that this diminution in thicki^ess 
continues across the state of Indiana into northern Illinois 
and southern Michigan. The outcrops of Ordovician strata in 
western and southern Illinois and in Missouri indicate a di- 
minution also in that direction. This suggests that the area in 
western Ohio and eastern Indiana was a region of maximum 
subsidence during the deposition of the Cincinnati series. Dur- 
ing this period the areas is southern Kentucky and northern 
Tennessee, and in western and northern Illinois were regions 
of less subsidence or at times possibly even of elevation. 
The wells in Ohio and Indiana do not indicate a decrease in 
thickness of the Cincinnati series from the flank towards the 
crest of the '' Cincinnati uplift along the western side of its 
present extension into these states. This suggests that the ori- 
gin of this part of the Cincinnati uplift may be of later date 
than the close of the Ordovician. Sufficient data have not yet 
been collected in Kentucky to determine whether the very evi- 
dent dome which now exists in north central Kentucky was 
already in existence in Ordovician times. The Cincinnati up- 
lift may have originated in southern Kentucky and northern 
Tennessee. The low fold which now extends, with a trend of 
25 degrees east of north, from Tennessee through central Ken- 
tucky may have been due to subsequent epeirogenic move- 
ments. Its northern extension into Ohio and Indiana may have 
been of still later date. It is evident that a nnich greater ac- 
cumulation of facts is needed before deductions can be made 
which will have any value excepting as offering suggestions 
of subjects for future investigation. 
t Geology of Ohio, vol. vi, 1H88. 
t 'Studies of the Indiana Natural gas field." Frank Lhvbrhtt, Amer 
Geol., vol. iv, 1889, p. 6. 
