[ells] Canadian geological nomenclature 21 



include sediments, ranging from the lowest Cambrian to the lower por- 

 tion of the Devonian. The true Silurian and Devonian rocks of this 

 district were found to occur as small infolded basins, in which the typical 

 fossils of these periods occur, though some of these sediments are in so 

 greatly altered a condition that, without such evidence, they might 

 readily be taken for Huronian rocks. As for the rest, though in certain 

 portions organisms, peculiar to the lower Trenton elsewhere, were 

 obtained, it has not as yet been possible to recognize all the divisions of 

 the geological scale in this area, though sufficient has been learned to 

 make the succession fairly complete for this section of the Palaeozoic 

 strata. 



The term Taconic employed by Emmons as early as 1841 for certain 

 rocks in the northern portion of Vermont and elsewhere in the district 

 south of the Canadian boundary, has never come into general use in our 

 nomenclature. It applied practically to the same series of formations, of 

 widely different horizons, Avhich were later described by Logan under the 

 head of the Quebec group already referred to. 



Eeturning to the consideration of the oldest rocks in Canada, or 

 the crystalline masses of the Laurentian and Huronian systems, we find 

 our nomenclature increased shortly after the advent of the latter term, 

 by the use of several new words. Thus in the Geology of Canada, 1863, 

 the names Lower and Upper Copper-bearing rocks were devised for a 

 peculiar series of slates, limestones, conglomerates and sandstones, with 

 which were intimately associated masses and dykes of trap (diabase) and 

 amygdaloids, found on the north side of Lake Superior, and concerning 

 the true horizon of which much dispute has since that date arisen. From 

 their lithological resemblance to certain rocks in Nova Scotia and else- 

 where portions of these were at one time regarded as possibly of 

 Triassic age. They have also been by some regarded as a portion of the 

 great Huronian series while by others they were held to constitute an 

 uucomformably overlying group. In connection with the upper Copper- 

 bearing rocks several new terms were introduced, among which may be 

 mentioned the Keweenaw, later changed to Keweenian series by Hunt, 

 and the Keweenawian by Major Brooks, of the United States Survey. 

 They have more recently been described under the names Animikie and 

 Nipigon groups; and the evidence from the most recent investigation 

 tends to place these peculiar rocks rather in the Cambrian system than 

 in the Huronian, while the trappean or diaba>e members of the series 

 may be regarded as newer intrusives or overflows in the slates and 

 limestones of that division. Any fossil remains which have been found 

 in the strata of this group of rocks are too indistinct to be of value in the 

 determination of horizons. 



