the mouth of the Clear Water River in lat. 56-1/2
degrees. In the two former localities the shale is in the neighbourhood
of horizontal strata of limestone; and in the latter it actually reposes
on the limestone, which extends in horizontal strata as far as Great
Slave Lake, is connected with many salt springs, and possesses many of
the characters ascribed to the zechstein formation. [Sidenote: 133]
Captain Franklin observed the beach under the shale cliffs of the
Mackenzie to be strewed not only with fragments of the shale, but also
with much lignite, similar to that which occurs at the mouth of the Bear
Lake River. Twelve or fourteen miles below these cliffs there is a reach
seventeen or eighteen miles long, bounded by walls of sandstone in
horizontal beds. [Sidenotes: 134, 135] Specimens obtained by Captain
Franklin at the upper end of the reach consist of fine-grained quartzose
sandstone[35] of a gray colour, and having a clayey basis, resembling
those which occur in the middle of Bear Lake River. At the commencement
of the "Great Rapid of the Mackenzie" there is a hill on each side of
the river, named by Captain Franklin the eastern[36] and Western
mountains of the Rapid. The Rocky Mountains appear at no great distance
from this place, running about N.W. by W., until lost to the sight; and
as the Mackenzie for forty or fifty miles below, winds away to the
northward, and, in some reaches, a little to the eastward, they are not
again visible, until the river has made a bend to the westward, and
emerges from the defile termed "the Narrows."

The "Eastern mountain of the rapid" seems to have a similar structure,
with the "Hill by the River's side," the hill at the mouth of Bear Lake
River, and the other limestone ridges which traverse this part of the
country. [Sidenote: 136] From some highly inclined beds near its base I
broke off specimens of a limestone, having an imperfectly crystalline
structure, and a brown colour, which deepens into dull black on the
surfaces of its natural seams. [Sidenotes: 137, 138, 139, 141] A piece
of dark-gray, compact limestone, having the peculiar structure to which
the name of "_cone in cone_" has been given, was found on the beach;
also several pieces of chert, and some fragments of a trap-rock,
consisting of pieces of greenstone, more or less iron-shot, cemented by
calc-spar.

Immediately below the rapid there are horizontal layers of sandstone
which form cliffs, and also the bed of