1885.] NATURAL SCIENCES OF PHILADELPHIA. 407 



NOTES ON THE LAFAYETTE SERPENTINE BELT. 

 BY THEO. D. RAND. 



It is well known that two nearly parallel belts of Serpentine and 

 Steatite cross the Schuylkill above and below Lafayette Station, 

 and pass southwestwardly towards the Pennsylvania Railroad. 

 The southeasternrnost, or steatite belt, cannot be observed beyond 

 a bend in the Black Rock road, about one-half mile north of the 

 railroad, the other was conspicuous at Rosemont Station, but no 

 outcrop was known southwestward until within three-fourths of a 

 mile of Darby Creek, on Meadow Brook, whence southwestwardly 

 it was continuous, or nearly so, to Palmer's mills on Crum Creek. 



This line is not easily identified with either of the former, but 

 I have recently found a distinct outcrop on the Roberts road, on 

 the property of Col. Jos. F. Tobias, or of Dr. Edward H. Wil- 

 liams, with fragments in the soil of the fields of the former to the 

 northeast. The belt is very narrow, and the valley of a small 

 creek seems to occupy r nearly the same line.* This outcrop is 

 about half way between the Rosemont and Meadow Brook out- 

 crops, and seems to prove beyond question that the belt crossing 

 Darby Creek is the Lafayette belt. On the Roberts road, north- 

 east of the Serpentine and measured at right-angles to the strike, 

 perhaps 100 to 200 feet distant, is a rock bearing great resemblance 

 to the Eurite of Barren Hill, Wayne, etc., occupying here almost 

 exactly the position relative to the Serpentine and the Laurent inn 

 axis that the Eurite does on the northwestwardly side of the 

 Laurentian, near Radnor Station. Its strike is N. 30° E., dip 

 50° to S. E. Adjacent mica schist N. 40° E., dip 65° to S. E. 



The position of this outcrop of Serpentine somewhat south of 

 the line of the Lafayette belt, indicates either a change in the 

 strike, or the echelon structure elsewhere observable in the Ser- 

 pentine of the adjacent region. 



