70 THE CAMBRIAN AND ORDOVICIAN DEPOSITS OF MARYLAND 



surface of this drusy quartz has a beautiful velvety appearance, the beauty 

 of which is enhanced by the lemon-yellow to brownish-olive color with just 

 enough reflection from the minute crystals to add a silvery sheen to the 

 surface. Other specimens of the same rock show these crystals increased 

 to a length of about 2 mm. and a magnified view exhibits their perfection 

 of form. These crystals are interesting in that practically all of those 

 observed are terminated by a single rhombohedron instead of the two 

 usually found in quartz. 



AREAL DISTRIBUTION. The geologic structure of the various occur- 

 rences of the Waynesboro formation in Maryland varies considerably. The 

 normal section from upper Tomstown through the Waynesboro into the 

 overlying Elbrook is present only in the strip of outcrops extending from 

 Benevola southwest to Burnside Bridge east of Sharpsburg, and even 

 here both ends of the strip are faulted. The ridge east of the Upper 

 Bridge and Middle Bridge of the Antietam battle-field exposes the 

 different divisions of the formation to best advantage for study. Here 

 only does the limestone middle portion form its characteristic topographic 

 feature of a valley between the two ridges left by the lower and upper 

 siliceous parts. Northeast of Benevola is a number of small outcrops 

 which in most cases are little more than surface remnants. The same 

 holds true of several lines of outcrop east of Chewsville where the rocks 

 are of such little depth that the underlying limestone is occasionally 

 plowed up in the fields. A shallow syncline commences one and a half 

 miles north of Smithsburg and terminates seven miles to the southwest 

 near Beaver Creek, one mile northeast of Wagner's Cross Eoads, in another 

 normal syncline. These two syncline terminal areas are connected by a 

 narrow strip of the formation in which the greater part of its thickness 

 is covered by overthrust faulting. Thus in the limestone quarry at Cave- 

 town the lower part of the Tomstown limestone is faulted against the 

 purple shales of the Waynesboro. An interesting anticline of Waynesboro 

 sandstone exposing the upper Tomstown with its characteristic black 

 banded chalcedonic chert in its axial part, enters the state from Pennsyl- 

 vania and is terminated by faulting at Ringgold. 



