GEOLOGICAL SOCIETY OF PENNSYLVANIA. 207 



sequently, if we take the mean of these observations, on 

 a meridian line of 22| miles, there must be added 4050 

 feet to the absolute descent of the Tioga river, and to 

 the thickness of several hundred feet of the carbonife- 

 rous formation. Thus there would need be a total height 

 of mountain of 5125 feet, at the state line, to contain the 

 coal measures; whereas the hills there are only 500 to 

 700 feet in their greatest altitude. This calculation is 

 entered into with a view of showing the futility of the 

 expectation, not uncommonly expressed, of tracing these 

 coal beds in a northerly direction beyond the limits at 

 W'hich they are at present discoverable. 



If we pursue this examination for the sake of a more 

 extended view of this great geological disposition to the 

 southward, our position will be remarkably strengthened. 



Thus, at 33 miles below Blossburg, the southern dip 

 continues at 198 feet in each mile; and at 38 miles, near 

 the Painted Post, is 130 feet per mile. At 42 miles, at 

 the Chimney narrows, near the entrance of the Chemung 

 Feeder, the dip is now flattened to about 100 feet per 

 mile ; making the aggregate southern depression of the 

 strata of old red sandstone about 1050 feet more, to be 

 added to 70 feet, the descent of the river to this point. 

 Uniting, therefore, these sums with that observed in the 

 Pennsylvania division of our section, the altitude of any 

 land or mountains near the Chemung river, capable of 

 containing the veins of the Tioga coal field, must be 

 more than 6000 feet, whereas they do not commonly 

 exceed 600 feet : or, by reversing the position, the stra- 

 tum of rock on a level with the river at the Chimney 

 narrows, if prolonged on an average plane of descent to 

 near Blossburg, would be about 6275 feet below the sum- 

 rait of the surrounding hills of the Tioga basin. 



I may add, that after having carried the examination 

 of the same series of rocks 60 miles further, or more 

 than 100 miles north and north east of the Blossburg coal 



