REPORT OP THE STATE PALEONTOLOGIST 1900 - 15 



contents has not jet been completely solved and can not be till 

 the collections which we have made from them are more 

 thoroughly studied. I have however given some time this year 

 to the reexamination of the formations in the field. 



Hudson river slates in the vicinity of Albany and their taxonomie 

 relations. The investigation of this important problem was. 

 placed in the hands of the assistant paleontologist, Dr Ruede- 

 mann, and progress was reported last year. During the present 

 year the examination of this formation has been extended to- 

 localities farther north, and results have been obtained confirm- 

 ing the propositions already put forward. The outcome of this- 

 work is the satisfactory demonstration of the fact that the great 

 mass of slates and sandstones in the Hudson and Mohawk valleys,. 

 which was termed by the early geologists the " Hudson river 

 slate " and given an independent position as a geologic unit in 

 the series of rock formations, is actually a peculiar local develop- 

 ment of several of the stratigraphic units as developed in the rock 

 sections farther to the west in the state — that they represent, in 

 fact, a part if not all of the Trenton limestone, the Utica slate and 

 the Lorraine beds, and that they have, therefore, no special fauna 

 which can be regarded as characterizing the Hudson river forma- 

 tion. This formation must therefore be interpreted as a local or 

 facies expression of the deposits of the three stages just men- 

 tioned. Dr Ruedemann reports in regard to this work that in 

 1899 the localities on the w est side of the Hudson river betweea 

 Coeymans and Waterford and on the east side between South 

 Troy and Castleton had been studied; to complete the investiga- 

 tion of the region selected, and the map, it was necessary to 

 trace the horizons established in the preceding season north- 

 ward through Troy and Lansingburg to a point opposite Water- 

 ford and over the islands in the Hudson river. Fossil-bearing 

 localities were found at Troy in several places, specially on Mt 

 Olympus and in the excavation around the new power-house 

 at Lansingburg. All of these localities contain graptolite 

 faunas, and that of the power-house several new species. The 

 faunas also proved the farther extension northward of the lower 



