Life's Dawn on Earth: Being the history of the oldest known fossil remains, and their relations to geological time and to the development of the animal kingdomDawson, John William, Sir
History
Life's Dawn on Earth: Being the history of the oldest known fossil remains, and their relations to geological time and to the development of the animal kingdom
Dawson, John William, Sir
Life -- Origin; Paleontology -- Precambrian
Before doing so, however, let us visit Eozoon in one of its haunts
among the Laurentian Hills. One of the most noted repositories of its
remains is the great Grenville band of limestone (see section, fig. 3,
and map), the outcrop of which may be seen in our map of the country
near the Ottawa, twisting itself like a great serpent in the midst of
the gneissose rocks; and one of the most fruitful localities is at a
place called Côte St. Pierre on this band. Landing, as I did, with
Mr. Weston, of the Geological Survey, last autumn, at Papineauville,
we find ourselves on the Laurentian rocks, and pass over one of the
great bands of gneiss for about twelve miles, to the village of St.
André Avelin. On the road we see on either hand abrupt rocky ridges,
partially clad with forest, and sometimes showing on their flanks the
stratification of the gneiss in very distinct parallel bands, often
contorted, as if the rocks, when soft, had been wrung as a washer-woman
wrings clothes. Between the hills are little irregular valleys, from
which the wheat and oats have just been reaped, and the tall Indian
corn and yellow pumpkins are still standing in the fields. Where not
cultivated, the land is covered with a rich second growth of young
maples, birches, and oaks, among which still stand the stumps and tall
scathed trunks of enormous pines, which constituted the original
forest. Half way we cross the Nation River, a stream nearly as large as
the Tweed, flowing placidly between wooded banks, which are mirrored in
its surface; but in the distance we can hear the roar of its rapids,
dreaded by lumberers in their spring drivings of logs, and which we
were told swallowed up five poor fellows only a few months ago. Arrived
at St. André, we find a wider valley, the indication of the change to
the limestone band, and along this, with the gneiss hills still in view
on either hand, and often encroaching on the road, we drive for five
miles more to Côte St. Pierre. At this place the lowest depression of
the valley is occupied by a little pond, and, hard by, the limestone,
protected by a ridge of gneiss, rises in an abrupt wooded bank by
the roadside, and a little further forms a bare white promontory,
projecting into the fields. Here was Mr. Love's original excavation,
whence some of the greater blocks containing Eozoon were taken, and a
larger opening made by an enterprising American on a vein of fibrous
serpentine, yielding "rock cotton," for packing steam pistons and
similar purposes. (Figs. 5 and 6.)
[Illustration: Fig. 5. _Attitude of Limestone at St. Pierre._
(_a._) Gneiss band in the Limestone. (_b._) Limestone with Eozoon.
(_c._) Diorite and Gneiss.]
[Illustration: Fig. 6. _Gneiss and Limestone at St. Pierre._
(_a._) Limestone. (_b._) Gneiss and Diorite.]
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