REPORT OF THE DIRECTOR I9IO Ij 



Professor Kemp, Doctor Berkey and Doctor Hollick has been 

 assigned the accjuisition of such data as will make a satisfactory 

 report on the geology of Greater New York — a work which ought 

 to be of large practical usefulness to architects, engineers and 

 municipal betterments generally in the city of New York. 



During the season Doctor Hollick has given his attention espe- 

 cially to the geological structure of Staten island both from surface 

 exposures and from the records of underground structure. 



Classification of the New York formations. The growth of 

 our knowledge and the refinement of our work has made desirable 

 a published restatement of the classification of the geological forma- 

 tions of the State. It is seven years since the last summary state- 

 ment of this kind was issued. There are now about 125 names 

 which have been applied to these formations — a bewildering num- 

 ber, but each has a value \Vhich requires exact definition for the 

 intelligent appreciation of our geology. 



SURFICIAL GEOLOGY 



In the northern part of the State, Professors Fairchild and Chad- 

 wick have studied the special features of Lake Iroquois and Gilbert 



The Lake Iroquois altitudes and limits in the region are now 

 approximately determined. In the valleys of the large rivers, as the 

 Grass, Raquette, St Regis and Chateaugay, the Lake Iroquois level 

 is indicated by delta sand plains of vast extent which agree in their 

 summit altitudes. The actual head of the easternmost of these 

 deltas, that on the Chateaugay, was examined. Here the boulder 

 and cobble deposits cover considerable area, and with the correlat- 

 ing lake features show a fairly definite altitude for the Iroquois 

 water at 980 feet, taking the railroad tracks at Chateaugay station 

 as 945. 



About 3 miles southeast of Russell on the meridian of Canton, is 

 a series of heavy cobble and gravel bars which have a summit alti- 

 tude of about 835 feet. The Iroquois plane between Watertown 

 and Chateaugay has a rise of about 2.27 feet per mile, in direction 

 northeast, and reaches Covey gulf, the point of escape, with an 

 altitude of about 1016 feet, or about 36 feet over the head of the 

 present channel. The fall of the lake level from the full-height or 

 Rome level to the Covey gulf level was probably not over 15 or 20 

 feet. This fall might have been by removal of drift or rock, or 

 down-cutting of the channel. 



