2IO - GEORGE W. STOSE 



tide, or current action. The thin fragments are often tilt d on 

 end, and resemble the "edgewise beds" of Missouri described and 

 figured by Nason.' Red clay in crevices and holes of the limestone 

 suggests surface weathering and residual clay filling solution pockets. 

 Oohte is evidence that the water was sufficiently shallow for the 

 waves to oscillate the particles on the sea bottom. For these reasons 

 it is concluded that this horizon represents a break of some conse- 

 quence in the sedimentation, due to uplift and erosion in this or 

 in some immediately adjacent territory. Since this change is accom- 

 panied by the introduction of a different fauna, specimens of which, 

 chiefly trilobites, collected at Scotland, were determined by Walcott 

 as Saratogan (Upper Cambrian), it is regarded as representing the 

 base of the Saratogan. Associated with the conglomerates is a 

 minutely laminated pure limestone with parallel, wavy, dome-shaped, 

 and contorted structures. Horizontal sections of the dome-shaped 

 structure show regular concentric rings, whereas the vertical sections 

 show waves with round tops and angular bottoms, as shown in 

 Fig. 3. No internal structures were observed by which organic 

 origin could be determined, but in a general way they resemble 

 Stromatopora and may represent some low form of life which spread 

 out on the sea bottom and secreted minute layers of lime. They 

 are undoubtedly similar to Cryptozoan proliferum described and 

 figured by Hall,^ which occur in oolitic limestone near the base 

 of the Saratogan in New York.^ 



The conglomerate zone, 10 to 15 feet thick, is followed by drab 

 magnesian limestone with the same Saratogan fauna, grading upward 

 into siliceous limestones containing occasional poorly preserved 

 gastropods of Beckmantown age. The formation is estimated 

 to be 2,000 feet thick. Ulrich, who has recently made a careful 

 study of the rocks throughout the Great Valley, regards this forma- 

 tion as stratigraphically and faunally the same as the Knox dolo- 

 mite of Tennessee, and the name "Knox limestone" is therefore 

 adopted. 



1 American Journal of Science, Fourth Series, Vol. XII, pp. 358-61. 



2 New York State Museum of Natural History Thirty-Sixth Annual Report 

 1883, Plate 6 and description. 



3 Walcott, Journal of Geology, Vol. XI, No. 3, pp. 318-19. 



