LAND DEFORMATION IN WESTERN NEW YORK 67 



and accepted by Dr Gilbert, as west 27 degrees north by east 27 degrees 

 south. The general direction of greatest nplift is normal to this or north 

 27 degrees east. In western New York, including the Seneca valley, the 

 isobases drawn between fairly well determined points of equal elevation 

 on the beaches of lakes Newberr}^ Warren, and Dana have a direction 

 lying between 17 degrees and 20 degrees south of east. This indicates 

 that the isobases of the greater area are curving lines with convexity 

 southward. In a recent paper* Dr Gilbert has so represented them. 



Data are now lacking for the accurate projection of the older water- 

 planes eastward of the Seneca valley, but the subsequent Iroquois shore 

 phenomena indicate but little east-and-west deformation, or, in other 

 words, that the direction of tilting, so far as the Iroquois plane is in- 

 volved, is not far from north -and-south in central New York. The Iro- 

 quois beach from Hamilton, Canada, with elevation 363 feet, to Rochester^ 

 New York, elevation 437 has an average rise of 0.66 foot per mile along 

 a line less than three degrees south of east. At the same rate of uplift 

 the Iroquois plane should have at the Rome outlet, which lies slighlty 

 north of the parallel of the beach at Rochester, an elevation of more than 

 510 feet. The elevation of the channel floor at Rome is about 440 feet. 

 It therefore seems likely that in central New York the isobases of the 

 later Iroquois are not straight lines, but curves with convexity toward 

 the south. Probably the older water-planes will be found to have, east of 

 the Seneca valley, isobases trending about 10 or 15 degrees south of east- 



In the Erie basin the Warren jtlane trends from Hamburg to Critten- 

 den about 50 degrees east of north. Regarding the beach elevation at 

 Hamburg as 815 feet and at Crittenden (at Lehigh Valley railroad sta- 

 tion) as 858 feet, with a distance of 23 miles, the average rate of uplift 

 is 1.87 feet per mile. The most northerly point of the Warren beach in 

 New York is 11.5 miles from Crittenden along the same line, with an 

 elevation of 887 feet, giving an uplift of 2.52 feet per mile. From Ham- 

 burg to the northernmost point of the beach (south of Smithville station 

 on the West Shore railroad) the average uplift is therefore a trifle over 

 two feet per mile in a direction 23 degrees nearer the isobase than the 

 theoretical direction of maximum upliit, north 27 degrees east. The 

 latter would be by calculation, 2.17 feet per mile and proportionally 

 greater as the isobase is nearer the parallels. 



Only in the Seneca and Cayuga valleys do we have sufficient north- 

 and-south distance upon the shorelines in central New York to make 

 any estimate of value regarding the northward uplift. The shoreline 

 phenomena are, in those valleys, chiefly wave-built embankments on 



*G. K. Gilbert : Recent Earth Movement in the Great Lakes Region. Elghteentli Ann. Rep. U. S. 

 Geol. Survey, p. 604. 



X— Bull. Geol. Soc. Am., Vol. 10, 1898 



