38 NEW YORK STATE MUSEUM 



IV 



REPORT ON THE GEOLOGICAL SURVEY 



AREAL GEOLOGY 



The past year has again made necessary some shortage of usual 

 activities in the geological survey of the State, which has for its 

 principal objective the completion of the map on the scale of one 

 mile to one inch. The State of New York is very large and a one 

 inch scale map means that field work in representing the distri- 

 bution of the geological formations and in making proper dis- 

 criminations of such formations so that its geological history may 

 be easily read, shall be carried out with the closest attention to 

 detail. The topographic or base map of New York is divided into 

 260 quadrangles, of which number about one-third have been 

 covered by the geological survey up to the present time. This work 

 should unquestionably progress more rapidly, and it will do so when 

 the financial condition of the Department is such that the greater 

 share of the appropriation can be allotted for it. A larger number 

 of expert geologists and very greatly increased facilities for print- 

 ing are required for the Department surveys in this direction. 



The field work on this survey has progressed during the past 

 year in western New York where Mr D. D. Luther has brought to 

 a conclusion his work in the region between Rochester and Buffalo. 

 Mr Luther's reports, not yet published, cover the quadrangles des- 

 ignated as Brockport, Hamlin, Albion, Oak Orchard, Medina and 

 Ridgway. 



In northwestern New York Professor Cushing carried to com- 

 pletion the areal mapping of the Brier Hill, Ogdensburg and Red 

 Mills quadrangles. The larger part of the area is occupied by early 

 Paleozoic rocks, and the results on the Precambric rocks were 

 reported a year ago. Some novel details have developed in the 

 Paleozoic rocks. 



The Potsdam sandstone continues across the area with much the 

 same character that it has in the .Alexandria and Clayton regions 

 farther west. It was laid down on an irregular floor and is thin. 

 The overlying Theresa formation, on the contrary, shows very con- 

 siderable differences when compared with the same more westerly 

 area. There it was thin, 30 or 40 feet only, and overlaid by an 

 equal thickness of beds which the fossils indicated to be o\ Tribes 



Hill age, corresponding to beds in the Mohawk vallev regarded as 



