1890.] NATURAL SCIENCES OF PHILADELPHIA. 91 



These schists continue about one-eifjhth of a mile to low ground 

 and a creek, southwest of which schists resembling the spangled mica 

 schist occur, and continue, poorly exposed, to the turnpike. The 

 strike of a bed of hard gneiss in the schist is N. 85° E. Here the 

 Pajjer Mill road ends, though shown on maps to continue. In fact 

 Thorp's Lane about .1 mile northwest continues to the Wissahickon. 

 On this, schists are seen with a strike N. 65° E. and soon the steatite 

 and serpentine N. 55° E. The road is nearly on this strike but a 

 little more southerly, so that near the creek it lies to the southeast 

 of the steatite which here appears to be synclinal, the schists to the 

 southeast regularly bedded dipping N. 40° W. 50° while the serpentine 

 rocks on the northwest side dip slightly S. E. The schists to the 

 northwest are about vertical. Here, as at the North Pennsylvania 

 Railroad, there has been an ancient gap in the Laurentian ridge 

 which further southwest appears as a very bold hill united with the 

 schistose hill at the Ridge turnpike, but toward the Schuylkill 

 separated from the schists by a valley in which the Lafayette serpen- 

 tine makes its appearance at its extreme northeast outcrop. 



If we study the rocks of Cream Valley, the corresponding rocks 

 on the northwest side of the Laurentian anticlinal, we find evidence 

 that the schists there are in connection with the Potsdam. 



In this narrow valley we find garnetiferous schists strongly resem- 

 bling some of those southeast of the Laurentian. Close to these, but 

 beyond them, is Potsdam, beyond it Rogers' altered primal, and 

 limestone. All seem to be conformable, and the schists and the 

 Potsdam appear at one locality northeast of Wayne to be inter- 

 stratified. The exposures are very poor. 



The altered primal includes pebbles of Laurentian, some of large 

 size. 



The Radnor serpentine appears to lie between the Laurentian and 

 these schists, and the northerly belt of steatite to lie in the schists, 

 similar to the relation southeast of the Laurentian, except that on 

 the S. E. there is a thin bed of spangled mica schists bearing very 

 strong resemblance to the mica schists of Cream Valley, between 

 the Laurentian and the serpentine. There is a connecting link 

 between the schists and the altered Primal of Rogers in peculiar 

 nodules, looking like pebbles, usually of a vitreous semi-transparent 

 colorless feldspar Avith perfect cleavage, apparently orthoclase. 

 While not uncommon they are not abundant in the rock. The 

 garnets are confined to the mica schists but much of the schist is not 



