THIRD REPORT OF THE DIRECTOR 1906 53 



ton's Landing, Dr Rttedemann has recorded a section where about 

 JOG feet of erect grit strata with Taonurus are both underlain and 

 overlain by dark argillites. The former, on account of the presence 

 of the Taonurus or " Cauda-galli fucoid " have been correlated as 

 " Esopus grit " by the Canadian geologists. The argillites, however, 

 both above and below these Taonurus grits, contain fossils ; a Dal- 

 manites nearer to the D. c o x i u s of the Grande Greve lime- 

 stone than any other that occurs to me and an Orthoceras with a 

 well defined and peculiar surface which I have not seen in other 

 species. There are traces also of other fossils. It seems hardly 

 an accurate expression to correlate these beds with the Esopus grit 

 of New York on the basis alone of the presence of Taonurus which 

 is now recognized as of direct or indirect mechanical origin and 

 occurs freely in sandy sediments of different ages. The fossils of 

 the adjoining conformable shales will determine the age of this de- 

 posit. At Owl's Head fossils were obtained from the altered lime- 

 stones ; these are chiefly corals, though brachiopods are also present. 

 The preservation is execrable but the corals, Favosites, Helio- 

 phyllum, Phillipsastrea and the brachiopods Atrypa reticu- 

 laris, Spirifer like S. acuminatus and a large Rhyncho- 

 nella, seem to entirely confirm the correlation by the Canadian 

 geologists with the Onondaga limestone. The two sections referred 

 to are several miles apart. 



The Rensselaer grit. Eastern Rensselaer and northern 

 Columbia counties are covered with a mantle of arenaceous deposits 

 lying unconformably on the upfolded Cambric and Lower Siluric 

 strata beneath. The character and distribution of this rock was 

 clearly outlined by Lieutenant Mather in his report on the first 

 geological district (1843) ^^^ its equivalence with the Shawangunk 

 grit of Ulster and Orange counties suggested. 



As the early geologists held the latter to be an eastern equivalent 

 of the Oneida grit of central New York, the Rensselaer grit has 

 consequently been assigned the same value in correlation. We owe 

 to T. Nelson Dale of the United States Geological Survey an inti- 

 mate knowledge of the stratigraphic relations of this terrane to the 

 unconformable rocks beneath and also the conclusion that the up- 

 folding of the lower and the upper terranes pertains to different 

 dates, the former to the Taconic uplift and the latter to the Post- 

 devonic or Carbonic uplift which also produced the more southerly 

 svnclinals now represented by Becraft mountain, Columbia co. 

 Mr Dale has correlated the Rensselaer grit with the entire Oneida- 



