"There is thus no absolute impossibility that distinct organic tissues may be found in the Laurentian graphite, if formed from land-plants, more especially if any plants existed at that time having true woody or vascular tissues; but it cannot with certainty be affirmed that such tissues have been found. It is possible, however, that in the Laurentian period the vegetation of the land may have consisted wholly of cellular plants, as, for example, mosses and lichens; and if so, there would be comparatively little hope of the distinct preservation of their forms or tissues, or of our being able to distinguish the remains of land-plants from those of Algæ. The only apparent plant of the Laurentian to which a name has been given, Archæophyton of Britton, from New Jersey, consists of ribbon-like strips, destitute of apparent structure, and which, if they are of vegetable origin, may have belonged to either of the leading divisions of the vegetable kingdom. I have found similar flat frond-like objects in the limestone of the Grenville series, at Lachute, in Canada.
"We may sum up these facts and considerations in the following statements:—First, that somewhat obscure traces of organic structure can be detected in the Laurentian graphite; secondly, that the general arrangement and microscopic structure of the substance corresponds with that of the carbonaceous and bituminous matters in marine formations of more modern date; thirdly, that if the Laurentian graphite has been derived from vegetable matter, it has only undergone a metamorphosis similar in kind to that which organic matter in metamorphosed sediment of later age has experienced; fourthly, that the association of the graphitic matter with organic limestone, beds of iron ore, and metallic sulphides, greatly strengthens the probability of its vegetable origin; fifthly, that when we consider the immense thickness and extent of the Eozoonal and graphitic limestones and iron ore deposits of the Laurentian, if we admit the organic origin of the limestone and graphite, we must be prepared to believe that the life of that early period, though it may have existed under low forms, was most copiously developed, and that it equalled, perhaps surpassed, in its results, in the way of geological accumulation, that of any subsequent period."
Figs. 20 and 21.—Bent and dislocated Quartzite, in contorted schists interstratified with Grenville Limestone, near Montebello.
The Quartzites have been broken and displaced, while the schists have been bent and twisted. In the immediate vicinity the same beds may be seen slightly inclined and undisturbed.
Let us take, in connection with all this, the fact that we are dealing with the deposits of the earliest ocean known to us—an ocean warm and abounding in the mineral matters suitable for the skeletons of humble animals, and fitted to nourish aquatic plants. The conditions were certainly favourable to an exuberant development of the lower forms of marine life; and in later times, when such conditions prevail, we generally find that life has been introduced to take advantage of them. The prudent farmer does not usually allow his best pasture to remain untenanted with flocks and herds, and the Great Husbandman of nature has, so far as we know, been similarly careful.
I add two sections showing the local disturbances of beds of quartzite and schist associated with the Grenville limestones ([Figs. 20 and 21, page 103]).
PROBABILITIES AS TO LAURENTIAN LIFE, AND
CONDITIONS OF ITS PRESERVATION
V
PROBABILITIES AS TO LAURENTIAN LIFE, AND
CONDITIONS OF ITS PRESERVATION
W