322 C. H. Smyth, Jr. — Peridotite in Central New York. 



A still more glaring error is to correlate Animikie — plainly 

 lower Cambrian, at least in Canada — with Huronian, with 

 which it has scarcely any feature in common. The difference 

 in degree of metamorphism exhibited under the microscope 

 has no necessary relation to age, but is dependent on local cir- 

 cumstances and probably still more on original characters. 

 There is no recognizable unconformity in this great Huronian 

 series, and the rocks composing it undoubtedly all belong to 

 the same rock-making era. The lapse of time represented may 

 be less than, or it may exceed, that of all subsequent rock- 

 making periods. On this point there is absolutely no evidence, 

 neither is there that it represents other than an unbroken and 

 very early, if not the earliest, series of events in the*history of 

 the evolution of the stratiform rocky crust. 



An important area of very characteristic Huronian rocks has 

 been recognized, during the past summer, on the east shore of 

 Lake Winnipeg, greenstones, " slate conglomerates." Keewatin 

 schists, etc. 



I have recently visited the districts of Madoc and Marmora 

 and I should now have no hesitation in, at least provisionally, 

 correlating the Hastings series of the late Mr. Vennor with 

 the Huronian, to which he himself surmised it was more nearly 

 related than to Laurentian. 



Art. XL. — A Third Occwrrence of Peridotite in Central 

 New York ; by C. H. Smyth, Jr. 



In view of the interest attaching to the demonstration by 

 Professor G-. H. Williams, of the igneous nature* of the so- 

 called serpentine of Syracuse, N. Y., any further occurrence 

 of similar rocks in this region seems worthy of note. 



A recent paperf describes several dikes near Ithaca, 1ST. Y., 

 consisting of a rock closely related to the Syracuse peridotite. 

 In both of these localities the dikes are associated with nearly 

 horizontal, undisturbed strata, differing in this respect from the 

 rock described in the present paper. This rock occurs in the 

 form of a narrow dike in a fault plane at the village of Man- 

 heim or East Creek, seven miles east of Little Falls, N". Y. 

 The dike is mentioned by Vanuxem in his description of the 



* G-. H. Williams : The Serpentine (Peridotite) occurring in the Onondaga Salt 

 Group at Syracuse, N". Y., this Journal, 1887, p. 144. Also Bull. Geol. Soc. 

 Arner., vol. i, pp. 533.' 534. 



f J. F.Kemp: Peridotite Dikes "in the Portage Sandstones near Ithaca, N. Y., 

 this Journal, November, 1891, p. 410. 



