270 New York State Museum 



These beds were formerly included in the "Hudson 

 River" group. Two graptolite zones are recognized (1 

 and 2), the Dictyonema flabelliformc fauna and the 

 Staurograptus dichotomies fauna. The fauna character- 

 ized by Dictyonema flabelliforme also occurs in Canada 

 and in Europe, where it is considered by some as belong- 

 ing to early Ordovician, by others as marking the closing 

 stages of the Cambrian (= Ozarkian). The total thick- 

 ness of the Schaghticoke shales is not known. Only about 

 50 feet are exposed but the thickness is probably consid- 

 erably more. 



The Tribes Hill limestone constitutes the basal Can- 

 adian in the Mohawk valley, resting nearly everywhere 

 on the Little Falls dolomite but its exact equivalent has 

 not been found in the Champlain valley or in the vicinity 

 of Saratoga Springs. This formation is also present in 

 the Ogdensburg and Thousand Islands region. It is a 

 sandy limestone. Weathering gives a peculiar gothic 

 fretwork appearance which in the earlier days (Vanuxem 

 '42) gave a basis for the name Fucoidal layers. This was 

 part of Vanuxem's "Calciferous" group of the Mohawk 

 valley. The limestone is quite fossiliferous and its Cana- 

 dian age is unquestionably indicated by the fossils. Asa- 

 phus and three or four other trilobites not known in 

 Ozarkian formations are found, the gastropod Eccy- 

 liomphalus multiseptarius, the brachiopod Dalmanella? 

 wemplei and the Ribeirias (crustaceans: branchiopods). 

 The Tribes Hill limestone varies in thickness up to about 

 40 feet. 



All the divisions of the Beekmantown limestone 

 (Clarke and Schuchert '99) have not yet been named. 

 The formation received its name from Beekmantown in 

 Clinton county where the typical development and fauna 



