PETROLEUM AND NATURAL GAS IN NEW YORK 403 



arches have not been found sufficient to effect a separation of the 

 petroliferous substances and the salt water. In the "Big Indian" 

 oil field of Monroe county, Ohio, many cases have occurred 

 in which three or four barrels of salt water are raised by the 

 pumps for every barrel of oil. The latter is, however, frequently 

 produced in amounts of hundreds of barrels in a day. 



The best defined monocline known is the Macksburg oil field 

 of Noble and Washington counties, Ohio. In this case it has 

 been demonstrated that the Berea grit has been checked in its 

 uniform descent to the southeastward, at the rate of 20' or 30' 

 of a degree and that it lies nearly horizontal for the space of one 

 mile. This horizontal portion has proved available as a store- 

 house of oil and gas, and a petroliferous production of consider- 

 able importance is distinctly referred to this structure, with gas 

 on its western boundary and salt water on the east. We owe 

 the determination of this monocline and the general facts of its 

 productive power, to F. E. Minshall, of Marietta. 



Coming back to New York, we find that it was invaded by 

 the Appalachian revolution with its mountain-making forces in 

 very much the same way that western Pennsylvania and eastern 

 Ohio were affected. Through the southern counties of the state, 

 low arches are produced, which lack the force necessary to make 

 them recognizable as features of the present surface relief, but 

 which, as exploration has proved, t were ample for the separation 

 of the oil and salt water that were tributary to its porous strata. 

 All the extensions of the great Bradford oil fields into Catta- 

 raugus and Allegany counties are examples. Of these the " Rix- 

 burg gas streak " is one of the best. 



But while the eastern side of the continent owes to the Appal- 

 achian revolution the great features of its relief, it has not been 

 limited to the orogenic activities of this period. Contraction and 

 necessary readjustments of the crust were certainly in operation 

 long before the close of paleozoic time, and the earliest formed 

 strata were left in an uneven condition. The steady growth of 

 the continent from the Canadian protaxis southward is respon- 

 sible for structural facts of great importance, specially for the 

 prevailing southerly dip that affects the entire state and that 



