476 A. \V. GRABAU- -PALEOZOIC DELTA DEPOSITS OF NORTH AMERICA 



teg-rated in parts: a 2 -foot bed of calcareous sandstone and a 6-foot bed 

 of light yellow sandstone. The under] vino- nodular limestones and shales 

 are referable to the Niagaran, as shown by their fossils. Overlying the 

 sandstones is a 4-foot bed of thoroughly disintegrated rock, stained brown 

 by iron hydrate and including rounded boulders of limestone, some of 

 them from 1 to 3 feet in diameter. The boulders are not residual, for 

 they are perfectly solid, only showing a certain amount of oxidation from 

 the surface down. They have the aspect of old limestone boulders worn 

 round during exposure to the air, probably by streams, and embedded in 

 a deposit of calcareous mud, rich in iron, which has since become disinte- 

 grated. This argues a period of exposure in post-Xiagaran time, as 

 indeed is also shown by the absence of the higher Xiagaran strata. The 

 intervening sandstone is, as shown elsewhere, referable to the Shawan- 

 gunk. Similar conditions exist farther east, but here the series is com- 

 plicated by the red sediments, as will be more fully discussed below. 



Considering all the sections, it seems impossible that any connection 

 could exist between the Salina basin and the Atlantic. It certainly could 

 not exist across Maryland, as sometimes suggested; for, as we have just 

 seen, the eroded Xiagaran surface is here succeeded by Lower Monroan, 

 with only an 11-foot, unfossiliferous sandstone series intervening, while, 

 moreover, indications of the existence of a long land surface are found 

 between the sandstone and the lower Monroan. 



Schuchert in his recent paleogeographic map of Salina time places the 

 connection in the northern New Jersey and southern Xew York area. It 

 is difficult to understand how such a supposition can be brought into 

 harmony with the sediments in this region; for it is just here that the 

 elastic sediments are at their thickest and their coarsest, and it is equally 

 plain that a large land-mass must have existed here and to the east which 

 supplied the materials of these clastic formations. This is not only 

 shown by the fact that the coarseness and thickness of the series are here 

 at the maximum, but also by the fact that there is absolutely no other 

 source than the great land-mass here which could supply such a volume 

 of sediment. This will appear fully as we discuss the sections in detail. 

 This postulate of a great land-mass as the source of the material in this 

 section is imperative, whether we consider the deposits in question marine 

 or continental. 



We may now proceed to a detailed discussion of the sections and their 

 significance. In all cases the question of continental versus marine ori- 

 gin of the deposits will be kept in mind during the discussion. 



Details of the seetions — In general. — In presenting the details of the 



