MARYLAND GEOLOGICAL SURVEY 91 



Geologists have heretofore limited it on the east by a boundary 

 line extending from Harris ville south to Frenchtown. It is true 

 that the exposures of granite-gneiss become much less conspicuous 

 or cease altogether in the vicinity of this old boundary. The fact 

 that east of this line lies the area of undissected plateau-land, which 

 has already been described as better serving the purposes of the agri- 

 culturist than of the geologist, explains the absence of exposures. 

 The soil remains the same as that to the west where it is visibly the 

 residual soil of granite. It is also uniform with that farther to the 

 east where streams are cutting through the plateau-land and exposing 

 a granite-gneiss. 



Moreover, obscure exposures and residual boulders of the granite- 

 gneiss are not altogether absent from the intervening area. Just 

 northwest of Principio, granite-gneiss is exposed. It can also be 

 seen in ledges and great boulders a little more than halfway from 

 College Green to Bay View. South of Bay View granite-gneiss is 

 exposed in Stony Run, Northeast and Little Northeast creeks, and 

 along the Baltimore and Ohio Railroad tracks. It has been quarried 

 at Leslie for the stone-work of the railroad trestle and a small quarry 

 has also been opened on Stony Bun, one mile southwest of Leslie. 

 There are fine exposures of the rock at the crossing of Northeast 

 Creek by the Pennsylvania tracks, and it may be seen in the bed of 

 the stream where it is crossed by the highroad from Perryville to 

 Elkton. This district, south of Bay View, is overlain by gravels and 

 the buried rock-formation is only exposed where the streams have 

 cut through the gravel. 



The rock of these exposures is either a hornblende-granite, or a 

 biotite-granite. It is a medium grained and light colored rock, tra- 

 versed irregularly by dark hornblende or biotite bands. It is a 

 massive rock as a whole, but may locally show extreme foliation. 

 The strike of the schistosity is northeast. It is essentially like 

 the Susquehanna granites, but cannot be advantageously quarried 

 because it is overlain by a considerable depth of decayed rock and 

 no stream has cut deep enough to expose the solid formation. 



