1890.] NATURAL SCIENCES OF PHILADELPHIA. 101 



Roberts' road a mile and a half south of the old Lancaster road, and 

 also on the Coopertown road (or Roberts' road as they run together) 

 west of the bridge over Darby creek, it becomes a coarse granite or 

 porphyry, containing, however, but little quartz. Some portions 

 exactly resemble part of the garnetiferous schist, northwest of the 

 Lauren tian, but I have nowhere observed garnets in it, though a 

 loose fragment of rock found on the Roberts road near MeadoAV 

 brook contained staurolite. 



The rock in contact with the LaFayette belt on its southeastern 

 margin is rarely visible at the point of contact. It may however 

 be seen at Rose's quarry, and also on the Roberts road east of 

 Meadow brook. It is a fine-grained mica schist, not contorted, not 

 wood-like in its fracture, like that near the steatite belt to the south- 

 east. It occasionally contains garnets but it is not distinctly 

 garnetiferous like that further southeast. 



It contains strata of schistose hornblende rock which, at one 

 locality 200 feet north of the West Chester and Philadelphia road, a 

 mile east of Newtown Square near the south line of Newtown 

 Township, appears to be changing into serpentine and these horn- 

 blende rocks are quite persistent, being found as far southwest as the 

 Willistown outcrop. 



The best exposure of this belt is at Rose's quarry near the Schuyl- 

 kill. Here the dip is 45° to 55° S. 30° to 40° E^ and beds of ser- 

 pentine above may be traced into enstatite below. Southwest are 

 large masses of enstatite in great quantity. This is also the case at 

 the outcrops on Darby creek and in Marple. Chromite was mined 

 near Darby creek in this belt. (Moro Phillips Chrome Mine.) 



The LaFayette belt may be traced by distinct outcrops from a 

 point about half a mile north of the Schuylkill to Rosemont station 

 P. R. R. Southwest of Rosemont, the outcrops are more indis- 

 tinct but careful search will disclose them between the old Lancaster 

 road and the Radnor and Chester road ; on this road a wide outcrop 

 suddenly appears and continues (except at Darby creek where some 

 low ground intervenes, beneath which it is doubtless concealed) to the 

 Philadelphia and West Chester road about a mile and a half east of 

 Newtown Square. Beyond this for a short distance it becomes in- 

 conspicuous or absent, but the ground is level and there are no good 

 exposures of any kind. About half a mile further southwest it is 

 again exposed as the great ]\Iarple outcrop, about a mile and a half 

 northwest of Palmer's Mill on Crum creek. 



