86 Brown — Silurian Limestone of Milesbtirg Gap. 



" The opening in the Lower Helderberg limestone referred to 

 by Prof. Rogers is evidently at Swoyer's quarry. The limestone 

 dips from 30°-40° N.W., showing a slip or crimple on the north 

 side with the edges turned up and dipping S.E. 10°. The lime- 

 stone is sparingly burned, and occurs in thin layers 2-3 feet thick, 

 intercalated with bands of gray argillaceous shale, and under a 

 cover of 8' of sandy soil derived from the mountain." 



Fig. 3. 



Fig. 3. Sketch map of the Milesburg region traced from the U. S. G. S. 

 map of the Belief onte Quadrangle. Hundred foot contours only are shown. 



The outcrop on the opposite (west) side of Spring creek he 

 describes thus :* 



"This rock makes quite a decided ridge and is again opened on 

 west side of Spring creek. In the opening the rock seems devoid 

 of fossils, is thin and siliceous, and beds for burning must be 

 selected with care. The whole formation, measured by outcrop, 

 is something like 1000' thick, though generally so covered as to 

 make careful measurements impossible. Bald Eagle creek at 

 Milesburg shows Oriskany s.s. No. VII outcropping in plates on 

 south side beneath the Bellefonte R.R. bridge." 



From this description it is quite evident that d'Invilliers 

 included under No. YI (Lower Helderberg limestone) all of 

 the beds between the so-called Clinton shale and the typical 

 sandstone of the Oriskany. In an appendix to the volume 

 quoted above (pp. 429-430) are a few notes on these beds by 

 A. L. Ewing of State College. He gives the following list of 

 fossils from the formation but does not say at what locality or 

 in what part of the beds they were found : Atrypa reticularis, 



* Ibid., pp. 281-282. 



