312 THE CAMBRIAN. Ibull.8Ji 



county, the basal sandstone rests upon the pre-Carabrian and contains 

 the Olenellus fauna. A few remainsof the latter have also been found in 

 the immediate superjacent limestone. The Middle Cambrian and Upper 

 Cambrian faunas occur in bedded limestones As the quartzite exposed 

 on the eastern side of the limestones of the "Marble Belt" represents 

 but a very small portion of the great series of shales, slates, etc., of 

 the Cambrian on the western side of the " Marble Belt," it is probable 

 that the lower portion of the limestone is of Cambrian age, the same 

 as in Dutchess County. This observation also applies to the basal 

 limestone in New Jersey and Pennsylvania, where there is very little 

 thickness of shales between the basal quartzites and the limestone. 1 



In central Virginia the lower 1,000 feet of the section is composed of 

 an alternation of shales and sandstones, while the upper 1,400 feet is 

 nearly all shales and slates, capped at the top by a rough siliceous 

 limestone. 



In Tennessee the quartzite is developed to a great thickness. The 

 quartzite is of Lower Cambrian age, and the Knox series of shales 

 are characterized in their upper portion by the Upper Cambrian fauna, 

 which passes above into the base of the great limestone series. As far 

 as known, the conditions in the sedimentation of the Alabama and 

 Georgia sections are very much like those of Tennessee. 



Briefly summarized, the sediments along the southern portion of the 

 coast line are sandstones followed by shales and limestones. More or 

 less variation occurs, but, as a whole, the change is gradual as we follow 

 the coast line to the north. In central Virginia, 300 miles to the north- 

 east, the argillaceous deposits are more abundant in the lower portion, 

 and they form the greater part of the upper series to the base of the 

 limestone. 



From Virginia northward across Maryland, Pennsylvania, and New 

 Jersey, and into New York, the argillaceous material accumulated in 

 relatively small proportion to the arenaceous beneath and the calcare- 

 ous above. How much of the latter is to be referred to the Cambrian, 

 is yet undetermined. Our knowledge of the series in Pennsylvania 

 and New Jersey is too limited to make an accurate comparison with 

 other sections. 



In western Massachusetts and Vermont and eastern New York there 

 are immediate coast-line deposits and also those of deeper water. 

 Along the coast line there was a great accumulation of sand, followed 

 by some argillaceous and then calcareous mud. Farther to the west 

 the argillaceous material predominates and the arenaceous and cal- 

 careous forms but a slight proportion of the great thickness of sedi- 

 ment. To the north these conditions remain until, in northern Ver- 

 mont, the calcareous matter predominates in the lower portion of the 



1 The announcement was made at the December meeting of the Geological Society of America at 

 Washington that the Olenellus fauna had been found in the quartzite in New Jersey, and Cambrian 

 fossiis in the limestones above the quartzite in New Jersey and at Rutland, Vermont. 



