458 PKOCEEDINGS OF THK ACADEMY OF [1894. 



to Compassville, being known further west as Sandy Hill.* On the 

 north side of this ridge the highly crystalline, hard, older gneiss ap- 

 pears, and in it, as usual, considerable trap, an outcrop of which 

 appears about three-eighths of a mile north of the ridge, and about 

 a half mile north of West Cain Meeting-house. 



The next outcrop of the northern series is on the farm of William 

 Paxson on the Philadelphia and Lancaster turnpike in West Sads- 

 bury Township, near the northwest branch of the Octorara Creek. 

 It is very insignificant and poorly exposed. On the Breou map it is 

 five miles S. 70 W. from the Brubaker outcrop. 



The easternmost outcrop of the southerly line is also poorly ex- 

 posed and insignificant. It is in Valley Township on the farm of E. 

 S. Umstead, one mile N. 70 W. from Coatesville and about a mile 

 and a half nearly south of the Windle outcrop.^ 



The next is also in Valley Township. It is on the farm of 

 William Hoofman, about a mile N. 45 E. of Pomeroy and two miles 

 S. 65 W. from the first. There is a large amount of the rock here 

 strewn in fragments over the surface. One mass only was apparently 

 in place, striking N. 65 E., the dip uncertain. Here cubic crystals 

 of probably limonite pseudomorph after pyrite were found. The 

 steatite is in smaller masses, softer, and apparently more nearly ap- 

 proaching pure talc than at the other localities. 



The third is the most extensive of these outcrops. It is in West 

 Sadsbury Township, five miles S. 85 W. from the second, and a mile 

 and a half N. 7 W. from Atglen. Here, on the Strasburg road, is 

 the Swan Tavern. North of it the Chester County gneiss is exposed® 

 and beyond this, the steatite, a short distance south of the Swan 

 Public School. The steatite, here accompanied by chlorite and a very 

 compact rock of a dull bluish color, soft but very tough, is in great 

 quantity but wholly in loose masses. On the road to Atglen, south 

 of the schoolhouse, a white fine-grained, highly feldspathic gneiss dips 

 N. 30 E. 60° ; an anomalous dip if the rock is iu place, as it appears 



* This prominent sandstone hill is not shown on the map in C*, though men- 

 tioned in the text on jiage 262 (Wagonville being evidently a typographical error 

 for Wagontown) and on p. 20, where it is referred to as an eastern extension of 

 Copper Mine T\idge, though on p. 161 it is included in the gneiss area. 



* This is in the area colored yellow on the map in ('*, where this color (repre- 

 senting the sandstone or quartzite) is widened suddenly and greatly after an 

 equally great narrowing northwest and north of Coatesville. If the typical 

 Cambrian sandstone is indicated my observations would not agree with this 

 widening, while if the ( "hester ( 'ounty gneiss is intended to be included they would 

 not agree with the narrowing. 



« C*, p. 270. 



