Prosser and Cumings — Lower Silurian Sections. 



651 



be the case later in this paper, at Crane's Village and Hoffman. As the 

 thickness of the Utica obtained in this section is much greater than any 

 previous estimate, it is interesting to review the former statements in regard 

 to its thickness. 



Emmons stated that the Utica slate " in the gorges of Lorrain and Rod- 

 man is about seventy-five feet thick ; it is, at least, less than one hundred 

 feet ;" 1 a statement which was repeated four years later in the Agriculture of 

 New York. 2 Vanuxem estimated that the maximum thickness of this for- 

 mation "is about 250 feet, 11,3 while Dana gave the thickness of the Utica 

 formation as 250 feet in Montgomery county. 4 More recent estimates are those 

 of Messrs. C. D. Walcott and C. S. Prosser, derived mainly from well 

 records. Walcott gave the thickness of Utica slate passed through in the 

 Campbell well- near Utica, as 710 feet; 5 and in a diagram 6 indicates that the 

 formation thickens eastward. In the section described by Mr. Walcott along 

 the south branch of Sandy creek in Jefferson county, he gave 180 feet of 

 Utica slate with 100 feet of transitional beds above, composed of "alternating 

 banks of shale and grey, fine grained, calcareous sandstone ; the shales pre- 

 dominating." 7 Prosser gave the thickness of the Utica slate in the 

 Chittenango well, thirty-two miles west of Utica, as 233 feet, below which are 

 sixty feet of transitional shale and limestone to the massive Trenton limestone. 

 In this well 640 feet of blue argillaceous shale and bluish-grey arenaceous 

 shale and sandstone are referred to the Hudson river. 8 In the Rochester well 

 the thickness of Hudson river and Utica taken together, is given as 598 feet. 9 

 In the Altamont well, about seventeen miles west of Albany, the drill started 

 595 feet below the base of the Helderberg limestone, which caps the Hudson 

 river formation in that vicinity, and passed through 2,880 feet of sandstone 

 and shales before reaching the Trenton limestone. 10 The thickness of Utica 

 slate was not ascertained in this boring, but a thickness of 3,475 feet of both 

 formations indicates a considerable thickness of Utica. Mr. Henry M. Ami 

 says: " By some of the early writers it [Utica formation] was spoken of as 

 consisting of shaly strata whose total thickness exceeded 900 feet, whilst by 

 others the very humble, yet perhaps truer estimate was given of about 



1 Geology of New York, Part II, 1842. p. 118. 



2 Loc. cit., p. 124 



3 Geology of New York. Part III, 1842, p. 56. 

 * Manual of Geology, Fourth Edition, p. 494. 



ap-oceetlings Amer.can Association Advancement of Science, Vol. XXXVI, p. 212. Also, Bulletin Geological Society of 

 America, Vol. I. 1890, p 347. 

 6 Ibid , p. 358 (diagram). 

 1 1bid.. p.34H, and see diagram on p. 850. 



8 Ibid., Vol. IV, p. 99. 



9 Proceedings of Rochester Academy of Science, Vol. II, p. 92. 



lOAshburner, Transactions American Institute of Mining Engineers, Vol. XVI. pp 931, 952. 



