The gneissic rocks within the immense area which has been described, no doubt represent a great period of geological time, and comprise a vast thickness of strata, the amount of which it would be impossible to determine with any degree of accuracy. Certain areas of a massive granitoid character, are regarded as “primitive” gneiss, and there is little doubt they are more ancient than those Laurentian rocks which are regularly and distinctly stratified, and consist of bands of different lithological characters, such as prevail in the Ottawa valley. As a general rule, in the great region around Hudson’s Bay, the gneiss is of a very monotimous character, consisting of the commoner reddish and greyish varieties. It is mostly massive, highly crystalline and hard, except where it has been exposed for ages to atmospheric influences, as in the non-glaciated districts. The fresh rock will break almost as easily across the lines of stratification as parallel with them. The average direction of the lamination is sometimes pretty constant over a considerable extent of country, but it is as frequently, greatly contorted on the small scale, and so much disturbed on the large scale as to render it almost impossible to trace out and map its structure. The gneisses of this kind are not known to carry any useful minerals, except such as mica and felspar in coarse granite veins. On the other hand, in the more southern districts, where the gneisses are somewhat regular, and where their different divisions are capable of being mapped, we find phosphate of lime, graphite, limestone, barytes, serpentine, magnetite and hematite, pyrites, galena, copper ores, &c. These rocks appear to be newer than the massive gneisses which prevail in the north. [Sidenote: Evidences of relationship in age.] The continuity and the geographical compactness of the great metamorphic or Laurentian area of the north-eastern part of the continent are themselves evidences of the close relationship in age of the rocks comprised within it, whereas there is more room for uncertainty on this point in reference to widely separated areas of metamorphic rocks more or less surrounded by newer formations. The various bands of rock which in Canada have been recognized under the name Huronian all lie within the general geographical limits of the Laurentian country, and are either stratigraphically incorporated amongst the members of the Laurentian series, or present no want of conformity to them. A variety of altered rocks, bearing a strong resemblance to those of some of the Huronian bands are found elsewhere, as in the Eastern Townships and New Brunswick, but their relations to the Laurentian system cannot be so easily determined. [Sidenote: Quartzites of Lake Huron.] [Sidenote: Associated rocks.] [Sidenote: Useful minerals in Huronian rocks.] [Sidenote: Geographical distribution of Huronian rocks.]