20 Indiana Natural Gas Field. — Leverett. 
water line in the gas fields of Indiana and Ohio. Since the an- 
ticlinal in Ohio is lower than that in Indiana and the amount 
of gas present is nearly as great as beneath an equal area of 
the Indiana anticlinal, the salt water line must be correspond- 
ingly lower. 
Oil. — Oil has been struck in several places along the north 
border of the gas field, in northeastern Grant and northern 
Blackford counties, and also in southern Adams county near 
Berne. A large tract along the line where oil is found has 
been leased by oil-companies with a view to determining the 
value of the field. When we bear in mind that the Findlay oil 
field comprises a belt scarcely five miles long and but two 
miles wide, including within this area some unproductive terri- 
tory, and yet contains a large number of profitable oil wells, it 
suggests the possibility that thorough exploration may bring to 
light one or more such fields in Indiana. 
Oil has been struck at Royal Center, in Cass county. At- 
tention has already been called to the higher altitude of the 
Trenton at this point. It is therefore an illustration of accum- 
ulation of hydrocarbons beneath anticlinals. We know of no 
borings in the vicinity of Royal Center which yield oil, but in 
this portion of the state deep borings are not so numerous as 
in the productive gas-field and its immediate borders. Alti- 
tude favors its occurrence along the line from Royal Center to 
Kentland but the rock texture may be unfavorable to oil or 
gas accumulation. We know, however, of nothing- that indi- 
cates a change in the texture of the rock from the porous con- 
dition it displays in the gas field ; on the contrary the outcrops 
of the upper portion of the Trenton in Illinois appear to be 
quite similar in structure to the Indiana gas rock. 
Rocli pressure. — Different theories have been advanced to 
account for the rock-pressure which the gas manifests. The 
one best substantiated ascribes it to the force exerted by the 
column of water which fills the Trenton from its outcrops in 
adjacent states down the inclined and porous portions of this 
limestone to the gas field. Here its pressure has driven the oil 
and gas into the anticlinals and terraces. This makes the 
gas expulsion a result of the same pressure that causes the 
water just outside the gas belt to rise from the Trenton in the 
form of artesian wells, and it is probable that as the gas be- 
comes exhausted, water will follow it up from below and even- 
