194 C. D. WALCOTT INTRA-FORMATIONAL CONGLOMERATES. 



glomerate appears to be within the range of this fauna, and points to an 

 intra-formational origin. 



The type that has already been described as occurring at Schodack 

 landing, New York, has been observed at many localities to the north, 

 in Washington county, New York, where it is a common feature of the 

 Lower Cambrian terrane. 



Pennsylvania Localities. — The succession of Cambrian rocks in York 

 and Lancaster counties, Pennsylvania, is very clearly defined. A mas- 

 sive quartzite is succeded by shales, and then a massive bedded, more 

 or less silicious limestone that varies in color and composition in its 

 several beds. This massive bed of limestone is succeeded in numerous 

 instances by beds of limestone conglomerate which are interbedded in 

 more or less thinly bedded, somewhat shaly limestones. One of the 

 most clearly defined sections is exposed at Bellemont, Lancaster county, 

 on the line of the Pennsylvania railroad. The massive blue and white 

 Cambrian limestones are succeeded by a few feet of a blue, earthy lime- 

 stone and shale, and upon this there is a bed of limestone conglomerate, 

 from eight to ten feet in thickness, that is made up largely of pebbles 

 and bowlders of limestone derived from the limestone beds beneath. A- 

 second bed of conglomerate is seen on the roadside to the north. 



About 40 miles west of Bellemont, at Stoners station, on the York 

 and Wrightsville railroad, York county, Pennsylvania, an extensive ex- 

 posure of the Lower Cambrian limestones and conglomerate is beauti- 

 fully shown in an old quarry just east of the wagon-road, one-fourth of 

 a mile north of the railroad track. Alternating bands of thinly bedded 

 limestone and massive beds of limestone conglomerate form about 100 

 feet of the exposed section, in which five beds of the conglomerate lime- 

 stone are well shown. The basal bed has a fine grained, gray limestone 

 matrix with brecciated limestone fragments in it which range in size 

 from that of small shot to masses three feet in diameter. These pebbles 

 and bowlers vary in lithologic character, some resembling the matrix 

 and others being oolitic, arenaceous, semi-marbleized and shaly lime- 

 stones. The thinly bedded limestones separating the conglomerate bands 

 are from four to six feet in thickness, and are very clearly defined. 



In the second band of conglomerate the larger bowlders occur in the 

 lower portion. The other three beds vary in details, but they are all 

 formed of the same type of rock. One of the upper beds contains a 

 multitude of small fragments of limestone. It was impracticable to ob- 

 tain a photograph of the basal beds, which contain the largest bowlders. 

 Plate 5 illustrates the evenly bedded limestones above and beneath the 

 third band, and also shows the character of some of the limestone bowl- 

 ders. In the shaly limestone at the base of this bed a large bowlder? 



