Miscellanies. 155 



Mohawk, a little below the lower aqueduct, it passes under the first 

 graywacke. 



This had been mistaken for second graywacke, on account of the 

 calciferous sandrock, (used as an indifferent water cement,) three 

 miles south, appearing to pass under it. We now discover that it 

 lies under that rock ; and that it is the same rock which forms the 

 banks of the Saratoga Lake, and the banks and bed of the Mohawk, 

 from near the Cohoes Falls, to Schenectady. — About midway be- 

 tween the Cohoes and Schenectady, is situated the remarkable crook- 

 ed slate ; being a variety of first graywacke. In it we find abundance 

 of the petrifactions found in siliceous slate, at Hudson, which has 

 been called Sertularia. It resembles the headed ear of barley ; 

 and on a former examination was, considered as a culmiferous plant. 

 But, as in numerous other cases, it is often difficult without numerous 

 specimens to decide, whether a petrifaction is animal or vegeta- 

 ble. As the lower orders of animals seem to have been " first en- 

 dowed with the gift of life," especially in great quantities, we are 

 disposed to refer most of the obscure petrifactions to the grand di- 

 visions of radiated and molluscous animals. This opinion has been 

 recently questioned. And stiped and culmiferous plants may have 

 preceded all animals. I leave therefore this petrifaction to future 

 examination. It is generally from one to three inches long, perfect- 

 ly plumose at its margin, with a body the eighth of an inch in diame- 

 ter. This is the same rock which is described in this Journal, and 

 illustrated by a drawing of the shore of Saratoga Lake, made by Dr. 

 J. H. Steel. 



At the meeting of the argillite and first graywacke, both rocks 

 are remarkably undulated throughout an extensive district, in the bed, 

 banks, and vicinity of the Hudson River. There is a remarkably 

 striking example near the commencement of the Hudson and Dela- 

 ware Canal on Hudson River at Esopus Strand. In all these places, 

 it seems as if there had been a great effort made by the argillite to 

 force the graywacke from its natural, horizontal position, into the in- 

 clined position of the argillite. 



175 M. Schenectady. The students visit the Rev. Dr. Nott at 

 Union College, he being president of the school as well as of that 

 college. They are entertained with much kindness. 



Sejyt. 3, 186 M.— Examine the very interesting calciferous sand 

 rock, called Flint Hill. The north side of this rock is cut down 

 and makes the bed of the canaL It is one of the strata comprised 



