wAi.coiT.l JOVIRONDACK SUB-PROVINCE. 207 



A short notice of the discovery of a massive limestone superjacent to 

 the typical Potsdam sandstone containing species of the Potsdam fauna 

 equivalent to the fauna of the upper horizon of the lower sandstone of 

 the Mississippi Valley was made by Mr. C. D. Walcott in 1884. The 

 limestone was originally referred to the Calciferous formation. 1 



Mention is made of the contact between the Potsdam sandstone 

 and the subjacent pre-Cambrian rocks in the vicinity of Fort Ann, 

 Washington County, New York, by Mr. G. E. Hall. 2 



A section of the Potsdam sandstone with the superjacent limestone, 

 carrying the Upper Cambrian fauna was published by Mr. C. D. Wal- 

 cott in 1886 accompanied by a list of the fossils found and a comparison 

 of them with the Wisconsin fauna referred to the Potsdam by Prof. 

 James Hall. 3 



In the fifth annual report of the State geologist of New York, in 

 some field notes on the geology of the Mohawk Valley, with a map, 

 Messrs. C. E. Beecher and C. E. Hall describe a section that occurs in a 

 cut on the West Shore Railroad at "Little Nose, Randall, Montgomery 

 County, New York." 4 In the woodcut illustrating the section, a breccia 

 that occurs unconformably beneath the Calciferous sandrock is stated 

 to contain Potsdam sandstone, crystalline limestone, quartzite, etc. 

 The evidence upon which the fragments of sandstone were identified as 

 of Potsdam age is not given. 



In a paper on a great Primordial quartzite Prof. N. H. Winchell re- 

 publishes a description of the Potsdam sandstone by Dr. Emmons and 

 correlates the formation with the "granular quartz" of the western 

 slope of the Green Mountains and the pre-Cambrian quartzites of Wis- 

 consin and Minnesota. 5 



In a paper read before the Geological Society of America, at Wash- 

 ington, D.C., December 31, 1890, Messrs. N. S. Shaler and H. S.Williams 

 described the presence of a thin bed of shale beneath the Calciferous 

 sandrock and just above a thin bed of sandstone that rests unconform- 

 ably upon the subjacent pre-Paleozoic rocks. The locality is a quarry 

 at Little Falls. In the shale numerous specimens of Lingidepis acumi- 

 nata were found. 6 



CANADIAN EXTENSION. 



In a report of progress of the geological survey of Canada for 1845-'46 

 Sir W. E. Logan notes the presence of a sandstone in the Ottawa dis- 

 trict, but is doubtful whether it represents the Potsdam sandstone, as 



1 Potsdam fauna at Saratoga, New York. Science, vol. 3, 1884, pp. 136, 137. 



'Laurentian Magnetic iron ore deposits from northern New York, accompanied by a geological map 

 of Essex County. Report of the State geologist for the year 1884. Albany, 1885, p. 32. 



3 Second contribution to the studies of the Cambrian faunas of North America. U. S. Geol. Survey, 

 Bull. No. 30, 1886, pp. 21, 22. 



4 Fifth Ann. Kept. State Geologist of N. Y., for 1885. Albany, 1886, p. 10. 

 * A Great Primordial Quartzite. Am. Geol., vol. 1, 1868, pp. 173-178. 



6 Unpublished. 



