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limestone valley, from northeast of Augusta to the Delaware 

 river. Its usual position is somewhat to the southeast of the 

 middle of the valley. Like many of the others, upon its south- 

 east it is not aKvays symmetrical, the strata on its two sides 

 dipping at different degrees of inclination, and being, besides, 

 often separated by either a crush of the rocks near their turn, or 

 by a partial dislocation immediately at the axis. 



West of Newtown the general belt of limestone is traversed, 

 for a space of several miles, by a narrow tract of the slate, 

 causing its northeastern termination to be in the form of two 

 wedge-shaped prongs, one ending near Courserville, the other 

 about three miles north of Newtown. 



This southeastern branch, from the main tract of the limestone, 

 contains, we have reason to believe, a lesser parallel anticlinal 

 axis, the cause, indeed, of the elevation of the limestone along 

 this line. Between it and the main axis, a little southeast of 

 Swartwoul's Pond, all the rocks have a synclinal arrangement, 

 the belt of slate lying in the middle of the trough of the limestone. 



Tracing the principal axis of the Paulinskill Valley beyond 

 the termination of the limestone near Courserville, we find it run- 

 ning for several miles further towards the northeast, until it passes 

 a little west of Deckertown, elevating the beds of the slate. 



The limestone valley of the Paulinskill corresponds accurately 

 in its general physical features with what is termed a valley of 

 elevation. 



Its strata having been upheaved along a central anticlinal axis, 

 the surface of the valley is somewhat raised in the centre, and 

 depressed along both margins, while the overlying and surround- 

 ing strata of slate, less broken and denuded than the limestone, 

 encompasses it in a regular escarpment, giving to the whole the 

 true structure of a valley of elevation. 



A much broader zone of slate is interposed between the 

 Paulinskill axis and that of the Newtown Valley, than between this 

 latter and the axis of the Jenny Jump and Pochuck range. This 

 is obviously the result of a twofold cause, the greater interval 

 which separates the two northwestern axes, and the less amount 

 of vertical elevation in the strata adjoining them : leaving, there- 

 fore, both a broader and deeper synclinal trough in the slate 

 to resist the denuding agency of the currents, which have swept 



