A Strati graphical Study 147 
study of the influence of springs in humid regions has been under- 
1 taken. 
|i (i) While mapping the stratigraphy of an area of approxi- 
j mately 25 square miles in central Ohio, where the annual precipi- 
jtation is about 40 inches, the influence exercised by springs was 
given particular attention. In this area the upper formations of 
^the Mississippian, and the lower of the Pennsylvanian periods 
come to the surface. The vertical series of rocks involves two 
; Fig. 9, Looking up-stream through the narrow, former col, part of Lost Run. 
j The section shown in Fig. 2 was measured beneath the trees standing on top of the 
I cliff in the middle distance. A primitive log house marks the location of a constant 
t spring. 
horizons of coarse clastic sediments, the Black Hand of the earlier 
period, and the Sharon member of the Pottsville, which is the 
lowest formation of the later period. The Black Hand overlies the 
Cuyahoga, which in central Ohio ‘‘is composed largely of bluish 
and grayish shales and buff sandstones. Subjacent to the Sharon 
is the Logan formation consisting chiefly of “bufl^ arenaceous 
shales to thin bedded sandstones. The Black Hand is a mas- 
” Charles S. Prosser: ‘Journal of Geology, vol. ix, p. 220, 1901. 
"/W., p.231. 
