and on the
first night, and from thence following the course of a small stream they
are conducted to the river _Inconnu_, and on the evening of the 4th day
they reach the shores of Esquimaux Lake. Its water is brackish, the tide
flowing into it. The neck of land which the Indians cross from Fort Good
Hope is termed "isthmus" on Arrowsmith's map, from Mackenzie's
information; and its breadth, from the known rate at which the Indians
are accustomed to travel, cannot exceed sixty miles. The ridge is named
the Carreboeuf, or Rein-deer Hills, and runs to lat. 69 degrees, forming
a peninsula between the eastern channel of the Mackenzie and Esquimaux
Lake.

A small stream flows into the Mackenzie some way below Fort Good Hope,
on the banks of which, according to Sir Alexander Mackenzie, the Indians
and Esquimaux collect flints. He describes these banks as composed of "a
high, steep, and soft rock, variegated with red, green, and yellow hues;
and that, from the continual dripping of the water, parts of it
frequently fall, and break into small, stony flakes, like slate, but not
so hard. Amongst these are found pieces of petroleum, which bears a
resemblance to yellow wax, but is more pliable." The flint he speaks of
is most probably flinty-slate; but I do not know what the yellow
petroleum is, unless it be the variety of alum, named rock-butter, which
was observed in other situations, forming thin layers in bituminous
shale.

About twenty miles below Fort Good Hope there are some sandstone
cliffs,[40] which Captain Franklin examined in 1825. [Sidenote: 173,
174] The sandstones are similar to those occurring higher up the river,
but some of the beds contain small pieces of bituminous shale; and they
are interstratified with thin layers of flinty-slate, and of
flinty-state passing into bituminous shale. [Sidenote: 175, 176] The
flinty-slate contains iron pyrites, and its layers are covered with a
sulphureous efflorescence. Some of the beds pass into a slate-clay,
which contains vegetable impressions, and some veins of clay-iron stone
also appear in the cliff.

Sixty miles below Fort Good Hope the river turns to the northward, and
makes a sharp elbow betwixt walls of sandstone eighty or ninety feet
high, which continue for fifteen or twenty miles. Captain Franklin named
this passage of the river "The Narrows."[41] [Sidenotes: 178, 179] The
sandstones of the _Narrows_ lie in horizontal beds, and have generally a
dark gray colour.