17 Classification of Rocks, 



17. PORTLAND STONE. 



18. KIMMERIDGE CLAY. 



19. CORAL RAG. 



20. OXFORD CLAY. 



21. GREAT OR BATH OOLITE. 



22. INFERIOR OOLITE. 



23. LIAS. 



24. UPPER TRIAS. 



25. MIDDLE TRIAS OR MUSCHELKALK. 

 •26. LOWER TRIAS. 



///.—PRIMARY OR PALyEOZOIC. 



27. PERMIAN OR MAGNESIAN LIMESTONE. 



28. COAL MEASURES. 



29. CARBONIFEROUS LIMESTONE, (Gaspe.) 



30. UPPER DEVONIAN. 



31. LOWER DEVONIAN. 



32. UPPER SILURIAN, 



33. LOWI3R SILURIAN. 



34. UPPER CAMBRIAN, 



35. LOWER CAMBRIAN. 



Tlie foregoing are all the rocks at present known which contain organic 

 remains, and considering that they would constitute, if all of them could be 

 found lying one above the other in their natural order, a thickness of ten 

 miles, composed altogether of the mud and sand which accumulated gradu- 

 ally in the ancient seas, one would suppose that the bottom rocks on which 

 the oldest of these rest would be the original surface of the earth — but it is 

 not so. Below the Cambrian there are other and more ancient stratified 

 rocks which proclaim the existence of seas still more remote in time than 

 those of the Cambrian age. They consist of hard rocks, which, in general 

 have been partly melted and re-consolidated — they are stratified, but much 

 bent and twisted together, and their surface presents unmistakeable evidences 

 of their having been greatly denuded or worn dov/ n by the long continued 

 action of atmospheric and other causes before the Cambrian system was 

 deposited upon their often upturneil edges. In Canada they occupy the 

 surface of nearly all the country lying on the north shores of the St. Law- 

 rence and Ottawa rivers, and the uninhabited territory between the Ottawa 

 and Lakes Huron. This latter region is also prolonged southwardly into the 

 United States, crossing the St. Lawrence between Kingston and Brockville. 

 The formation has received the name of The Laurentian from Mr. Losran. 

 The country occupied by it is generally rough and broken up into ragged 

 hills and valleys, with numerous small lakes of beautiful clear watef well 

 stocked with fish. 



Although these rocks, the Laurentian, are certainly of secondary origin, 

 that is, were formed at the bottom of some vastly ancient sea, after the crea- 

 tion of the world ; yet, on account of their wide diffusion, for they, with- 

 out doubt, underlie ail the fossiliferous rocks, they may be assumed for our, 

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