88 THE CRYSTALLINE ROCKS OF CECIL COUNTY 



successive belts, trending alike northeast-southwest across the plateau. 

 Their areal distribution will be outlined briefly and can be readily 

 understood with the assistance of the accompanying geological map. 



MicA-Giraiss. 



Among the crystalline formations of the county there is but one 

 that is of sedimentary origin. This origin is greatly obscured by 

 complete metamorphism. The rock is a very schistose gneiss, vary- 

 ing from a somewhat coarsely crystalline muscovite-biotite-gneiss to 

 a finer grained miiscovite-chlorite-gneiss, or to a chloritic quartzite. 

 It may be conglomeratic, or it may show distinctly marked quartzose, 

 micaceous, and gneissic beds. It is best exposed on the Susquehanna 

 river from Bald Friar Station northwest to the State line. It appears 

 here in a succession of bold cliffs, 100 to 150 feet in height. The 

 cliffs approach the water's edge on both sides of the river and give 

 rise to the wildest scenery of the county. 



At Wildcat Point a cleft in the rock, forming a passage some 50 

 feet in depth, is known as Wildcat cave. At this locality the strike 

 of the formation is X ± 60° E. 



At Bald Briar the strike is ^ 75° E. Elsewhere the strike lies 

 between 35° and 55° east of north. 



The stratification when shown is uniformly inclined to the south- 

 east and varies in dip from 30° to 80°. 



The areal distribution of the gneiss in the northwestern corner of 

 Cecil county is limited to an equilateral triangular area, whose sides 

 are approximately two and one-half miles in length. 



It is cut off on the southeast by intrusive igneous material, and 

 encloses a considerable body of the same character. The gneiss 

 passes over the state boundary into Pennsylvania, where it is an 

 extended and important formation. It is areally continuous to 

 the east in Lancaster and Chester counties in Pennsylvania, but in 

 Cecil county the northeastern area is separated from the northwestern 

 area by igneous intrusives. The northeastern area has for a northern 

 and eastern boundary the State lines. Its southern boundary is an 

 east and west line, giving it a width north and south of a mile to one 



