The same
eminent palaeontologist has also described undoubted worm-burrows
from rocks probably of Laurentian age. Further and more extended
researches, we may reasonably hope, will probably bring to light
other actual remains of organisms in these ancient deposits.
THE HURONIAN PERIOD.
The so-called _Huronian Rocks_, like the Laurentian, have their
typical development in Canada, and derive their name from the
fact that they occupy an extensive area on the borders of Lake
Huron. They are wholly metamorphic, and consist principally of
altered sandstones or quartzites, siliceous, felspathic, or talcose
slates, conglomerates, and limestones. They are largely developed
on the north shore of Lake Superior, and give rise to a broken
and hilly country, very like that occupied by the Laurentians,
with an abundance of timber, but rarely with sufficient soil
of good quality for agricultural purposes. They are, however,
largely intersected by mineral veins, containing silver, gold,
and other metals, and they will ultimately doubtless yield a rich
harvest to the miner. The Huronian Rocks have been identified,
with greater or less certainty, in other parts of North America,
and also in the Old World.
The total thickness of the Huronian Rocks in Canada is estimated
as being not less than 18,000 feet, but there is considerable
doubt as to their precise geological position.
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