STATE GEOLOGIST. 143 
In this well the Cow Run sand was absent, its place being occupied 
by the sandy shales lying from 40 to 65 feet above the Cambridge lime- 
stone. This would make the interval between the base of the Ames lime- 
stone and the top of the Cow Run sand 7o feet, and this is the distance 
that is usually given along Oliver run. However, a quarter of a mile 
distant, along Buck run, the interval is 90 feet, and this 1s about the normal 
distance between these two formations in southeastern Ohio. The appa- 
rent contraction of the section along Oliver run raises the question whether 
the oil sand there is not a “stray” and the place of the Cow Run sand occu- 
pied by the black shales, which directly overlie the Cambridge limestone. 
Salt-water is found everywhere in the field, but usually not in suf- 
ficient quantities to cause serious trouble to the operator. Fresh water is 
commonly found in the limestones (““blue-cores’”’) above the Ames and in 
the latter stratum, and salt-water in the Cow Run sand. In the early days 
water was shut from the well by the “seed-bag,” which consisted usually 
of a leather bag filled with flax-seed, but occasionally oats, wheat or some 
other grain was used. The bag was tied around the tubing at such a point 
that when put in the well, it would stand just below the point at which the 
water entered. The grain becoming wet would swell, completely filling 
the hole, and thus prevent the water from reaching the oil sand. 
The Oi! Sand.—This is a clean, porous, quartz sand. The quartz is 
colorless and distinctly vitreous. Usually the grains are angular, but oc- 
casionally a well-rounded one is found. The rock, which is the First Cow 
Run sand, is much more open than the Berea. It has a thickness ordinarily 
less than 25 feet, the oil being found in the upper 10, and salt-water be- 
low. It is overlaid by a fine-grained shale, sometimes called soapstone by 
the driller. : 
Here, as elsewhere, the sand does not form a continuous layer, but 
is patchy. It may run out, and be replaced by a shale in a very small 
area, so there is more than the usual chance of failure in this formation. 
Not infrequently a belt in which the sand is wanting may run directly 
across a productive strip. If the Berea grit be taken as a representative of 
the persistent beds of the state, then the First Cow Run may be selected 
to represent the opposite type. Its treachery is unusual for even a sand- 
stone. 
The sand does not contain sufficient gas to make the wells flow. 
Search has been made in the deeper rocks with the hope of finding suf- 
ficient fuel to pump the wells, but this effort has been only partly success- 
ful. Four small gas wells have been found near the junction of Oliver and 
Buck runs in a seam of coal reported 7 feet in thickness, and lying 205 
feet below the Ames limestone. This is the position of the Upper Freeport 
or No. 7 coal. 
Oil Production.—The largest well that has ever been secured in the 
field did not produce more than 100 barrels per day. At present the 
