324 REVIEWS GEOLOGICAL SURVEY OF CANADA. 



eastern extremity of the Province, sufficiently points out that the lineal range of 

 the lime-feldspars will be co-extensive with Canada, We may therefore antici- 

 pate a beneficial result from their influence upon the soils, over the whole breadth 

 of the Province. 



The ruins of the crystalline limestone constitute a most fruitful soil, so much 

 so that the lots first cleared in any settled area of the Laurentian country, usually 

 coincide with its range. In these limestones phosphate of lime is sometimes 

 jaresent in great abundance, and there is scarcely ever any large exposure of them 

 examined, in which small crystals of the phosphate are not discernable by the 

 naked eye. Mica and iron pyrites, are present, to furnish other essential ingre- 

 dients, and the easily disintegrating character of the rock readily permits its re- ' 

 duetion to a soil. The effects of these limestones and lime-feldspars are not 

 however confined to the immediate localities in which the beds are found, for 

 boulders of them are met with transported to southern parts, even far on the 

 fossiliferous rocks beyond : and there can be little doubt that their fragments are 

 very generally mixed with the soils of the Laurentian country. Thus while the 

 diversity of minerals in the difl'erent rocks of the series furnishes the ingredients 

 required.to constitute good soils, the agency of the drift has mingled them, and 

 considering the resistance to disintegration offered by most of the rocks, with the 

 exception of the limestone, the deficiencies that may exist will rather be in the 

 quantity of soil covering the rocks in elevated parts, thau its quality where the 

 materials have been accumulated. 



Mr. Murray's explorations during the period embraced in these 

 Reports, were carried on principally in the wide and little-known tract 

 of country between the north shore of Lake Huron, east of Spanish 

 river, and the upper part of the Ottawa. Besides a general geological 

 investigation of this district, Mr. Murray has communicated a large 

 amount of important topographical information, illustrated by a series 

 of no less than' twenty-two maps of various lakes and rivers, laid 

 down, from his own measurements, on a scale of an inch to the mile. 

 Labors of this kind, unknown to the geological surveyor of old coun- 

 tries, serve to shew the difficulties with which our Canadian survey 

 has still, in great part, to contend. Large districts must be mapped 

 by the explorer, before the results of his explorations can be worked 

 out ; and hence, the skill of the practised surveyor has to be com- 

 bined with that of the geologist proper. It is not every geologist, 

 however, who is capable of responding to this additional demand. 



With the exception of a few outlying patches of Lower Silurian 

 strata in the islands of Lake Nipissing, and in the valley of the Bonne- 

 chere, the rocks of this district, as determined by Mr. Murray, belong 

 to the Laurentian and Huronian series, overlaid in places by drift clay 

 and sand, with occasional boulders ; and traversed at many points by 

 intrusive and intercalated masses of greenstone, and dykes of trap and 



