Maryland Geological Survey 403 



northeast of Jennings Eun, wliei'e it was determined by Professor Steven- 

 son as 1980 feet.' Dr. White in his section along the Potomac llivcr gave 

 the tliickness of the Catskill as 1300 feet." 



Exposure on Braddock Run. — The Catskill is exposed in the cuts of the 

 Cumberland and Pennsylvania E. E. west of Allegany Grove. 



No. 1. An estimate of the thickness of the Catskill formation was 

 made which was measured by zones. The first one is from the western 

 end of the trestle to the eastern end of the second cut; the horizontal 

 distance is 900 feet, determined by counting the rails as in all the zones, 

 but the general direction is N. 10° E. so that the distance for measuring 

 the thickness is only about 378 feet. The dip is G0° which gives a 

 thickness of 327 feet for this zone. 



No. 2. Extends from the east end of the above cut to the eastern end 

 of the tunnel in the Catskill. The dip at the east end of the cut is 

 60° to 63°, average 61°, and at the western end 71°, making an average 

 dip, for the cut, of 66°. Horizontal distance 510 feet which would give 

 a thickness of 464 feet but on account of a heavy curve in this zone this 

 would be an overestimate. The general direction, however, from the base 

 of this zone to the top of the formation is nearly at right angles to the 

 strike. The rocks are red shales and sandstones, except at the eastern 

 end where there are some greenish-gray sandstones. 



No. 3. The Catskill tunnel, dip at eastern end 62°, at western end 

 64°, average dip for tunnel G3° ; horizontal distance 390 feet, giving a 

 thickness of 347 feet for the tunnel. 



No. Jf. From the western to the eastern end of the cut is 420 feet 

 horizontal. Dip in cut 52°, making an average dip of 58° and giving a 

 thickness of 357 feet for the zone. The rocks at the western end of the 

 tunnel are largely l)rownish-red sandstones which are quite massive. 



No. 6. This zone runs from the eastern end of the first cut east of 

 the Pocono tunnel to the grayish Pocono sandstones at the eastern end 

 of the tunnel. The rocks consist largely of red argillaceous shales alter- 

 nating with quite massive, brownish-red, micaceous sandstone. In the 



'T-, 1882, pp. 73, 103. 



»Proc. Amer. PhiL Soc, Vol. XIX, 1882, p. 443. 



