3^3 



1886.1 u<J*J [Brannor. 



Pot-holes. 



Among the interesting local phenomena related, in one way or another, to 

 the glaciation of this valley, are the great pot-holes found near Archbald' 



As the first one of these pot-holes is described in detail by Mr. Ashburner, 

 I will only mention here, in speaking of the second one, what appear to 

 be some of the important facts that relate to, or bear upon, their common 

 origin. 



The first of these holes was discovered in February, 1884, by the miners 

 of Jones, Simpson & Co. cutting into it where it had penetrated the Arch- 

 bald bed of coal in the Ridge mines. It was full of sand and water-worn 

 material, and the surface of the ground, being covered with forest, 

 showed no evidence of its presence. It is situated near the loot of the 

 mountain, two miles clue north-west of the town of Archbald, and nearly 

 a mile south-east of the Callender gap. The little hollow in which both 

 the holes are situated is half a mile long, and, in this distance, rises about 

 ninety-five feet in the direction of N. 32° E. At the lower end this hollow 

 broadens out, the hill-tops on either side being about five hundred feet 

 apart, and about seventy feet above the top of the first hole, which is at 

 the lower end of -the hollow. A small, wet-weather stream runs down 

 this hollow during the greater part of the year. 



The second pot-hole is in the bottom of the same hollow 1100' N. 33° E. 

 from the first. At this point the hill on the north-west is only about ten 

 feet above the level of the stream, while the one to the east rises almost 

 perpendicularly about sixty feet above it. The location of the second or 

 upper hole was discovered in May, 1885, in the same manner, and by the 

 same parties that discovered the first one. Sand and water-worn drift, in 

 every way similar to that found in the first hole, fell into the breast when 

 the opening was made. To prevent further inconvenience in working 

 this part of the mine, the material was propped up, and confined with 

 pillars, to keep it out of the breasts. Not having been cleared of its con- 

 tents it is impossible to describe this hole in detail, but with the aid of 

 information kindly furnished me by Mr. Edward Jones of Jones, Simpson 

 & Co., the operators of these mines, I am able to give its position and 

 depth. The former, was determined by the mine map. The depth was 

 obtained by using the mine levels, which give the elevation of the bottom 

 of the hole, and my own topographical survey of this vicinity, which gives 

 the elevation of the surface at this point. 



Elevation A. T. of the rail at the mouth of the drift 1077.95' 



Rise to the bottom of the second or upper pot-hole 49. 50' 



Elevation A. T. of the bottom of second or upper pot hole. 1127.45' 

 Elevation A. T. of Topographical Survey station 3372, 



which is almost exactly over the hole 1192.07' 



Total depth, including surface 64.62' 



Surface — say 14.62' 



Approximated depth of pot-hole 50.00' 



PROC. AMER. PHILOS. SOC. XXIII. 133. 2s. PKIHTED APRIL 15, 1886. 



