R^SUM^, AND GENERAL DISCUSSION. 521 



" On this point we have recently convinced ourselves, by clear and indisput- 

 able sections, that the lowest beds charged with anything like animals or vege- 

 tables are the exact equivalents of the Lower Silurian strata of the British 

 Isles, and that these have been distinctly formed out of, and rest upon, slaty 

 and other rocks which hud undergone crystallization before their particles were 

 ground up and cemented together to compose the earliest beds in which or- 

 ganic life is traceable. To the crystalline masses which preceded that paljeozoic 

 succession to which our researches were mostly directed, we apply the term 

 'Azoic,' not meaning thereby dogmatically to affirm, that nothing organic 

 could have been in existence during those earliest deposits of sedimentary mat- 

 ter, but simply as expressing the fact, that in as far as human researches have 

 reached, no vestiges of liWng things have been found in them, so also from 

 their nature they seem to have been formed under such accompanying condi- 

 tions of intense heat and fusion, that it is hopeless to expect to find in them 



traces of organization In the term Azoic rocks, we include all the 



crystalline masses belonging to the ancient group of gneiss, together with 

 ancient granitic and plutonic rocks by which they have been invaded."* 



It will be noticed that Murchison considered that his " Azoic " rocks 

 — in Scandinavia, at least — seemed to have originated under such 

 conditions that the existence of organic life at the time of their forma- 

 tion was impossible; yet, as he hastens to add, he was not willing 

 "dogmatically to affirm" that these rocks might not contain fossils. 

 It is not easy to understand exactly what ]\Iurchison meant by these 

 two evidently contradictory statements; but this want of tenacity of 

 opinion in regard to the truly azoic character of the infra-Silurian rocks 

 was still further exemplified in the various editions of his " Siluria," in 

 the course of which we see the author passing gradually from an up- 

 holding of a sei'ies of necessarily non-fossiliferous " bottom rocks," up to 

 a positive recognition of the Laurentian and Huronian systems of the 

 Canada Survey, and the admission that the rocks designated as " Azoic " 

 and said to be necessarily azoic, did furnish proofs of the existence of 

 life on the globe at the time of their formation. f 



* Proc. Geol. Soc. London, Yol. TV. (1845), p. 602. The Geology of Russia in 

 Europe, and the Ural Mountains, Vol. I. (1845), p. 10. 



t In the fii-st edition of "Siluria" (1854), the rocks called in "Russia and the 

 Ural Mouutains " Azoic are designated by the term " Bottom Rocks," and they are 

 said to " lie below all those formations in which there are the slightest vestiges of 

 Silurian life." These rocks are also said to have been "formed, as I [Murchison] 

 believe, at a period when the heat of the earth was antagonistic to the existence of 

 living beings." In the third edition of the same work — the second is not at hand 

 for reference — the Azoic rocks are designated as "primeval" and "fundamental," 

 and it is said that " they inay have been formed at a period when the heat of the 

 earth was antagonistic to the existence of liWng beings." In the fourth edition of 



