MARYLAND GEOLOGICAL SURVEY 97 



The lower Stonehenge limestone is made up in large part of very 

 massive blue to dove-colored limestone weathering bluish-white or 

 white. The outcrops are always of a distinctly lighter color than the 

 associated formations. This feature is one of several that serve unmis- 

 takenly in identifying this basal zone of the formation. On close inspec- 

 tion a large part of these massive limestone ledges appears to the un- 

 assisted eye as granular in texture, but under a lens the granules prove 

 to be very small brecciated pieces of limestone usually less than a sixteenth 

 of an inch in diameter. These small fragments are of a more distinctly 

 white color than the surrounding matrix and the combination of a light 

 blue rock crowded with lighter colored minute angular fragments is very 

 distinctive. The lower division is further distinguished by absence of 

 chert. In all of the numerous outcrops that have been studied no chert 

 of any kind has been observed either in the weathered limestone or in the 

 soil derived from it. At intervals varying from an inch to two inches the 

 limestone develops very thin layers of carbonaceous or argillaceous 

 material which gives it a banded aspect. These layers or laminae are 

 usually about one-eighth of an inch in thickness, flat and parallel with the 

 bedding planes. They are quite unlike the sandy intertwining laminae so 

 characteristic of the upper division of the Stonehenge member. 



Along the National Highway just south of Funkstown there are 

 splendid outcrops of typical lower Stonehenge limestone where fossils 

 may be found and its lithologic character can be studied to advantage. 

 Hagerstown and vicinity also affords numerous, excellent and instructive 

 exposures of those beds. 



Excepting the shells of a few brachiopods the fossils in this zone cannot 

 be cleanly extracted from the rock because they are so firmly cemented 

 to the fine-grained matrix that in breaking the limestone with a hammer 

 the fracture passes through the fossils and not along their surfaces. It 

 is only upon the weathered surfaces of the ledges that the fossils can be 

 discerned, and at that merely as cross-sections. The exposures near 

 Funkstown have shown clearly that the fossils of the lower Stonehenge 

 fauna, especially the cephalopods and gastropods which constitute much 



