THE IMPERFECTION OF THE GEOLOGICAL RECORD 293 



tian formation of Canada is generally admitted. There are three 

 great series of strata beneath the Silurian system in Canada, in 

 the lowest of which the Eozoon is found. Sir W. Logan states that 

 their "united thickness may possibly far surpass that of all the 

 succeeding rocks, from the base of the palaeozoic series to the 

 present time. We are thus carried back to a period so remote, that 

 the appearance of the so-called primordial fauna (of Barrande) 

 may by some be considered as a comparatively modern event." 

 The Eozoon belongs to the most lowly organized of all classes of 

 animals, but is highly organized for its class; it existed in count- 

 less numbers, and, as Dr. Dawson has remarked, certainly preyed 

 on other minute organic beings, which must have lived in great 

 numbers. Thus the words, which I wrote in 1859, about the exist- 

 ence of living beings long before the Cambrian period, and which 

 are almost the same with those since used by Sir W. Logan, have 

 proved true. Nevertheless, the difficulty of assigning any good 

 reason for the absence of vast piles of strata rich in fossils be- 

 neath the Cambrian system is very great. It does not seem prob- 

 able that the most ancient beds have been quite worn away by 

 denudation, or that their fossils have been wholly obliterated by 

 metamorphic action, for if this had been the case we should have 

 found only small remnants of the formations next succeeding 

 them in age, and these would always have existed in a partially 

 metamorphosed condition. But the descriptions which we possess 

 of the Silurian deposits over immense territories in Russia and in 

 North America, do not support the view that the older a forma- 

 tion is, the more invariably it has suffered extreme denudation 

 and metamorphism. 



The case at present must remain inexplicable, and may be truly 

 urged as a valid argument against the views here entertained. To 

 show that it may hereafter receive some explanation, I will give 

 the following hypothesis. From the nature of the organic remains 

 which do not appear to have inhabited profound depths, in the 

 several formations of Europe and of the United States; and from 

 the amount of sediment, miles in thickness, of which the forma- 

 tions are composed, we may infer that from first to last large 

 islands or tracts of land, whence the sediment was derived, oc- 

 curred in the neighborhood of the now existing continents of 

 Europe and North America. This same view has since been main- 

 tained by Agassiz and others. But we do not know what was the 

 state of things in the intervals between the several successive 

 formations; whether Europe and the United States during these 



