146 
Frank Carney 
tion is prevailingly coarse; locally it is exceedingly coarse. A 
variation along horizontal lines is the most striking feature of the 
Sharon. The transition laterally from fine, even-textured sand- 
stone, to irregularly bedded conglomerate masses ranging from 
quartzite pebbles to units 4 or 5 inches or even larger of siliceous 
fragments, was long ago noted by geologists in Ohio. The evi- 
dence of regressive continental sedimentation in the Sharon is 
quite conclusive. Terrestrial streams here have followed a 
retreating shore line, their flood plain and alluvial fan deposits 
being indicated now by the coarser phases just alluded to. Such a 
transportation of river deposits would be witnessed in a tilt or 
warp of an ocean-border tract, the movement progressing inland. 
Thus in the littoral zone finer sediments would accumulate, irregu- 
lar in horizontal distribution because of vigorous streams, a condi- 
tion less favorable to fauna; these sediments, the Logan, would 
suffer erosion locally, and in the channels thus made later sedi- 
ments, the Pottsville, were deposited. 
The patches of fire-clay and of coals found in the upper Sharon 
and later Pottsville indicate a balanced condition between ero- 
sion and deposition which insured a wide littoral zone and the 
development inland of extensive flood-plains. 
I 
c. Geographic Influences Arising from this Stratigraphy^ 
In the arid southwest parts of the United States, the crude water 
signs of the Indians have often pointed the white man to a spring. 
The government topographic maps covering sections of this region 
of sparse rainfall give the location of many springs. Throughout 
the longer-known and more-traveled desert areas of the world, the 
few oases have fixed the routes taken by caravans. Numerous books 
are available detailing facts that bear on the geographic influence 
of springs in arid climates. But into whatever land man has gone, 
humid as well as arid, springs have had a part in his activities. So 
far as America is concerned, I am not aware that a quantitative 
D. White: Bull. Geolog. Soc. Am., vol. xv, p. 279, 1904, urges that a trans- 
gressing sea was associated with the deposition of the Pottsville sediments. 
The remainder of this paper is reprinted from The Popular Science Monthly, 
vol. Ixxii, pp. 503-11, 1908, where it appeared under the title, “Springs as a Geo- 
graphic Influence in Humid Climates.” 
