388 F. REPORT OF PROGRESS. E. W. CLAY POLE. 



The development of the coral bed in the southern expo- 

 sures of the limestone shale is remarkable. In the typical 

 section at Clark's mill it contains scattered but abundant 

 masses of Stromatopora and a Facosites or Fenestella. In 

 this quarry ii exhibits a mass 5 feet thick of more or less 

 siliciiied masses of the former genus with a few interspersed 

 nodules of the latter, generally if not always, calcareous. 

 Many of these can be cleaned by the use of muriatic acid 

 and give a fair representation of the original form. 



The Orlskany sandstone, No. VII. 



The map of Spring township given herewith shows that 

 the course of the Oriskany sandstone is exceedingly erratic. 

 To understand the nature and cause of this complexity the 

 map must be compared with the section across the strata. 

 It will then be seen that the superficial lines on the map are 

 merely the outcrop of folded and contorted beds which have 

 been forced into their present position during the general 

 crumpling to which the strata in this part of the State have 

 been subjected. 



Only a few of the more conspicuous or determinate can here 

 be noticed. The ridge south of Elliotsburg is a continuation 

 of that which appears at Half Falls mountain, forming a 

 dam across the Juniata. It passes thence close to Pine 

 Grove church, may be seen south of Bloomfield, and thence 

 traced along the valley westward. 



The ridge crossing the road at the residence of the Messrs. 

 Rice near Landisburg comes almost in a straight line from 

 the Perry furnace, and is called in this report the North 

 Furnace ridge. At the Perry furnace it turns round the 

 anticline and returns west-southwest almost parallel with 

 the preceding until it ends in a. high bluff above Adam's 

 Q-len school-house two miles north <>f Bridgeport. Here the 

 Perry county fault, to he presently noticed, cuts across it, 

 producing^ however, a very small displacement, 



Another line of this sandstone enters the township at 

 Gibson's mill after running down the north side of Sandy 

 hollow. Hence it forms the north bank of Sherman's creek 



