CANADA. 337 



rocks of Lake Huron, and therefore those of Lake Superior, were rc- 

 ganled as being of Cambrian age. 



In the Report of Progi-ess for 1848-49, Mr. Murray again reported 

 on the region north of Lake Hui'on. He arranges the rocks along the 

 Spanish Elver into two series : the granitic or metaviorphic group, and 

 the quartz rock group. The first group " appeared to rise from beneath 

 the rocks of the second group in two ditfercnt locaHties," but no evidence 

 seems to have been found to show the relations of the two supposed 

 formations except the finding of pebbles of granite or syenite in some of 

 the conglomerates of the second gi'oup. The rocks of the first group 

 were said to be granite or syenite, except the following : — 



" A gneissoid structure was observed on one or two occasions, but it was for 

 the most part obscure and ill-defined, being perceptible rather in a longitudinal 

 arrangement of the constituent minerals, than in conspicuous beds of different 

 quality." (/. c, pp. 36-42.) 



In the Report of Progress for 1849-50, a tract of country on the St. 

 Lawrence River, between Bay St. Paul and Murray Bay, was described. 

 Here the metamorphic group, consisting of gneiss, was overlain by 

 white quartz rock (Potsdam sandstone). {I. c, pp. 8-10.) In the Re- 

 port for 1851—52, the meiaino7phic or gneissoid group) is likewise said 

 to be overlain by Potsdam sandstone in the country between Beauhar- 

 nois and the Riviere du Noi'd. {I. c, p. G.) 



In the Quarterly Journal of the Geological Society (Vol. VIII., 1852, 

 p. 210), ^Ir. Logan states regarding the rocks north of Lake Huron : — 



" On Lake Huron the Lower Silurian group rests unconformaldy upon a 

 siliceous series -with only one kno\\Ti band of limestone, of about 150 feet 

 thick, with leaves of chert in abundance, but as yet •without discovered 

 fossils. This series is supposed to be of the Cambrian epoch. It compre- 

 hends the copper-bearing rocks of that district, and with its igneous inter- 

 stratified masses has a thickness of at least 10,000 feet. The gneissoid group, 

 of which mention is made, is probably still older than this. Its conditions 

 appear to me to make it reasonable to suppose that it consists of aqueous de- 

 posits in an altered state." 



In the Report for 1852-53, but published in 1854, ^Mr. Logan 

 writes : — 



" The name which has been given in previous Reports to the rocks underly- 

 ing the fossiliferous formations in this part of Canada is the Metamorphic 

 series, but inasmuch as this is applicable to any series of rocks in an altered 

 condition, and might occasion confusion, it has been considered expedient to 

 apply to them for the future, the more distinctive appellation of the Laiu-entian 



VOL. TII. — NO. 11. 22 



