e Elk River. The traders report that
there are extensive deposits of sandstone on the eastern arm of the
Athabasca Lake, and, perhaps, these sandstones extend nearly to
Clearwater River. Sand covers the limestone on that river to the depth
of eight or nine hundred feet, and the fragments of sandstone in it are
large, numerous, and not worn.

The quantity of gypsum in immediate connection with extremely copious
and rich salt springs, and the great abundance of petroleum in this
formation, together with the arenacious, soft, marly, and brecciated
beds interstratified with the dolomite, and above all, the circumstance
of the latter being by far the most common and extensive rock in the
deposit, led me to think that the limestone of the Elk and Slave Rivers
was equivalent to the zechstein of the continental geologists. My
opinion, however, on this subject is, from a total want of practical
acquaintance with the European rock formations, of little weight; and
several eminent geologists are, after an examination of the organic
remains and mineralogical characters of the specimens brought home,
inclined to consider the formation as analogous to the carboniferous or
mountain-limestone of England.

As to the limestone formation of Lake Winipeg, I have no doubt of its
identity with that occurring in the islands at the passage of La Cloche,
in Lake Huron, and also with that at Cape Parry and at Cape Krusenstern,
on the coast of the Arctic Sea. It is probable, also, that these four
deposits belong to the same epoch with the limestone of Elk and Slave
Rivers, although they differ in containing little or no petroleum. It is
proper to mention, however adverse it may be to the opinion I have
ventured to hint at above, of these extensive horizontal deposits of
limestone being referable to the zechstein, that the limestone of Lake
Huron is generally considered as belonging to the mountain-limestone;
and Professor Jameson, from a review of the organic remains occurring in
the Lake Winipeg deposit, considered that it also belonged to that
formation. The formation of Cape Lyon may be, with less danger of a
mistake, referred to the transition or mountain-limestone.

THE END.

[Illustration]

FOOTNOTES:

[20] This was estimated by allowing one foot descent per mile for Bear
Lake River, whose length is seventy miles; and three inches per mile for
the descent of Mackenzie River, from the junction of the former river to
the sea, being a