86 THE CAMBRIAN AND ORDOVICIAN DEPOSITS OF MARYLAND 



undulations rises in the stratum to a height of two feet or more. This 

 Cryptozoon sometimes consists of a single mass of strongly marked undu- 

 lating layers one-half inch apart rising in the rock like a column. Speci- 

 mens may be seen to advantage two miles northwest of Leitersburg along 

 the road south of Millers Chapel, and along the Western Maryland Rail- 

 road just west of Charlton, Maryland. This particular Cryptozoon is of 

 special interest in having oolites one-eighth of an inch in diameter 

 abundantly developed in the areas between the dow'nfolds of the lamina- 

 tions (see pi. IX, fig. 2). The formation of these oolites appears to have 

 been connected with the life activities of the plant. 



Edgewise Conglomerate. 



These peculiar conglomerates are such a marked feature of the Conoco- 

 cheague limestone that they are described at this point, although they 

 occur equally well developed in subsequent formations. The typical dark- 

 blue, banded and frequently crinkled limestones of the Conococheague 

 formation, are often separated by layers varying from a few inches to a 

 foot or more in thickness, composed of a rather homogeneous or slightly 

 granular rock filled with long, slender fragments of a distinctly different 

 limestone tilted at various angles to the bedding plane. The actuality of 

 the difference in composition of the two rock types making up such layers 

 is not conspicuously evidenced on a freshly fractured surface, but weather- 

 ing causes the slender fragments to stand out quite prominently upon 

 exposed surfaces. The position of the fragments frequently on end or on 

 edge in the matrix has given the common name of edgewise beds to such 

 strata. Some of these fragments are sharp-edged and show no evidence 

 of wave action ; others are rounded at one or both ends and have appar- 

 ently been worn. Often the matrix of these conglomerates contain small, 

 rounded quartz grains, evidently derived from some nearby land area. 



These edgewise beds have long been considered as intraformational 

 conglomerates and under a broad definition of that term they could still 

 be considered so. However, the original intraformational conglomerate 

 described by Walcott did not include this type. All of his examples are 



