Page:The Outline of History Vol 1.djvu/33

 land here and there, either not covered by later strata or exposed after vast ages of concealment by the wearing off of the rock that covered them later—there are great surfaces of them in Canada especially; they are cleft and bent, partially remelted, recrystallized, hardened and compressed, but recognizable for what they are. And they contain no single certain trace of life at all. They are frequently called Azoic (lifeless) Rocks. But since in some of these earliest sedimentary rocks a substance called graphite (black lead) occurs, and also red and black oxide of iron, and since it is asserted that these substances need the activity of living things for their production, which may or may not be the case, some geologists prefer to call these earliest sedimentary rocks Archæozoic (primordial life). They suppose that the first life was soft living matter that had no shells or skeletons or any such structure that could remain as a recognizable fossil after its death, and that its chemical influence caused the deposition of graphite and iron oxide. This is pure guessing, of course, and there is at least an equal probability that in the time of formation of the Azoic Rocks, life had not yet begun.

Long ago there were found in certain of these ancient first-formed rocks in Canada, curious striped masses, and thin layers of white and green mineral substance which Sir William Dawson considered were fossil vestiges, the walls or coverings of some very simple sort of living thing which has now vanished from the earth. He called these markings Eozoon Canadense (the Canadian dawn-animal). There has been much discussion and controversy over this Eozoon, but to-day it is agreed that Eozoon is nothing more than a crystalline marking. Mixed minerals will often intercrystallize in blobs or branching shapes that are very suggestive of simple plant or animal forms. Any one who has made a lead tree in his schooldays, or lit those queer indoor fireworks known as serpents' eggs, which unfold like a long snake, or who has seen the curious markings often found in quartz crystals, or noted the tree-like pattern on old stone-ware beer mugs, will realize how closely non-living matter can sometimes mock the shapes of living things.

Overlying or overlapping these Azoic or Archæozoic rocks come others, manifestly also very ancient and worn, which do