290 W. J. Miller — Ice Movement and Erosion, 



The width varies greatly but averages about 15 miles. The 

 following topographic maps of the TJ. S. Geological Survey 

 cover most of the region : Port Leyden (aud northward and 

 eastward), Pemsen, Little Falls, together with portions of the 

 Wilmurt, Boonville, and Utica quadrangles. (See sketch map.) 



The chief topographic feature of the northern portion of the 

 area is the Black river valley through which Black river flows 

 in a northwesterly direction. This valley is from 10 to 15 miles 

 wide and shows a maximum depth of about 1300 feet. West 

 Canada creek, the principal tributary of the upper Mohawk 

 river, traverses the southern part of the area. This southern 

 part is very hilly and shows a general slope towards the Mohawk 

 river. The watershed separating Black river and West Canada 

 creek represents one of the principal divisions of drainage in this 

 part of the state. Leaving the Mohaw T k river at Utica (eleva- 

 tion 400 ft.), and passing northward along the R. W. & O. R. R., 

 there is a gradual ascent to the divide (elevation 1280 ft.) 

 south of Alder creek. From this point northward there is a 

 gradual descent along the railroad to near Lowville, where 

 Black river shows an elevation of 740 ft. The common range 

 of altitudes along both the eastern and western sides of the 

 district is between 1200 ft. and 2000 ft. 



The Paleozoic-Precambrian boundary line passes lengthwise 

 through the region. The Precambrian rocks comprise chiefly the 

 highly metamorphosed Grenville sediments, the post-Grenville 

 syenite-gneiss, and large areas which are more or less intimate 

 mixtures of the Grenville and syenite. The Paleozoics overlap 

 on the Precambrians and exhibit an excellent section showing 

 the Pamelia sandy limestones, Lowville limestones, Black 

 river shales and limestones, Trenton limestones, Utica shales, 

 Lorraine shales and sandstones and the Oswego sandstone. 

 The type localities of the Lowville, Black river and Trenton 

 are found here. 



The full significance of the glaciology of this territory will 

 not be known until the contiguous areas have been carefully 

 studied. The discussion here presented is local in its charac- 

 ter, the purpose being to record observations and to offer some 

 conclusions which may aid in the solution of the broader prob- 

 lem. So far as the writer is aware, nothing has been published 

 regarding the northern portion of the district, while Cham- 

 berlin,* Brigham,f and Gushing;}: have each referred to the 

 southern portion. Brigham is now engaged in the study of 

 the Mohawk valley region. § 



* Third Annual Eep. U. S. G. S., 1881-2, pp. 360-365. 



fBull. Geol. Soc. Am., vol. ix, pp. 183-202, 1898. 



JN. Y. State Museum, Bull. 77, pp. 73-81, 1905. 



§ Since the above was written several papers bearing on the glacial history 

 of Central and Northern New York have been read by H. L. Fairchild before 

 the 1908 meeting of the Geological Society of America. 



