0F THE NEW RED SANDSTONE FORMATION OF PENNSYLVANIA. 
13 
the Dreissena of Vanbeneden, (D. polymorpha,) which inhabits the Volga and other 
rivers of the north of Europe, and which has been transferred to, and diffused 
throughout Great Britain. 
Professor Ansted states that “ the whole of the upper new red sandstone of England 
bears evident marks of its marine origin, even if the occurrence of so large a quantity 
of salt associated with it, did not place the matter beyond a doubt. The almost total 
absence of fossils is, however, a very remarkable phenomenon, and one which is not 
satisfactorily accounted for, either by the prevailing sandy character of the deposit, 
or by the quantity of oxide of iron distributed through it.” 
The diffusion of salt mentioned here, and which is also w r ell known to prevail 
throughout the formation in England, and on the Continent, is totally absent in the 
New Red Sandstone of this country, and in this character they altogether differ from 
each other. The salines of the United States are in the older palaeozoic rocks, having 
their origin below the carboniferous series, but sometimes passing through the coal 
rocks to the surface, from the Silurian strata below.* 
In May, of last year, I visited the locality of Upper Milford, in the hope of finding 
some other portions of the Clepsysaurus, or the remains of other animals in this 
locality. A diligent search was made, with the assistance of Dr. Shelley and 
another person, but we were not able to detect the smallest indication of further 
specimens. One of the principal objects of my visit was to ascertain clearly the 
position of the rocks from which the bones, in possession of the Academy, were 
exhumed. The spot, pointed out to me by Dr. Shelley, was at the point of a hill, in 
the excavation of which, for a road, the rocks were blasted, leaving a perpendicular 
wall of the confused calcarious conglomerate rock, which was here composed of small 
portions, cemented by a reddish or greyish, somewhat argillacious, paste, presenting 
the appearance of masseration, while in other localities the same rock has quite a 
brecciated and beautiful structure. This locality is near to the north-western 
boundary of this New Red Sandstone formation ; and, in an early part of this paper, 
I have traced it to the South-west, across the Schuylkill, Susquehanna, and Potomac 
rivers. 
In the present state of our knowledge of this calcarious portion of the red sandstone 
deposit of the United States, it is exceedingly difficult to come to a satisfactory 
conclusion as to its exact equivalent in Europe. On the whole, I am inclined to 
place it among the superior strata of the Permian system. I do not see any portion 
of the Magnesian Limestones, which present characters more analogous to ours than 
the 11 Brecciated and Psmdo-brecciated Limestones''' 1 of Mr. King’s “Monograph of 
* The Onondago Salt group gives origin to all the productive salines of New York. It constitutes No. 12 of the 
New York Survey: is part of No. 5 of the Pennsylvania survey, and forms the middle portion of the Upper Silurian 
of English geologists. 
