the river. Captain Franklin
obtained specimens of this stone, which do not differ from the
sandstones above the rapid. [Sidenote 142, 143, 140] And amongst the
debris of the cliff he found other specimens of the "_cone in cone_,"
such as it occurs in the clayey beds of the coal measures, and also some
pieces of crystallized pyrites.

[Sidenote: 144, 144a, 145, 146, 147, 144b] About forty miles below the
rapid, the river flows through a narrow defile formed by the approach of
two lofty banks of limestone in highly-inclined strata, above which
there is a dilatation of the river, bounded by the walls of sandstone,
which have weathered, in many places, into pillars, castellated forms,
caves, &c. The sandstone strata are horizontal, have slate-clay
partings, and seams of a poor clay-iron stone, but do not differ in
general appearance from the sandstone beds at the rapid, except that a
marly stone containing corallines, and having the general colour and
aspect of the sandstone beds, is associated with them at this place.

The very remarkable defile, below these sandstone beds, is designated
"the _second rapid_" by Sir Alexander Mackenzie, and "the _ramparts_" by
the traders, a name adopted by Captain Franklin. Mackenzie states it to
be three hundred yards wide, three miles long, and to have fifty fathoms
depth of water. If he is correct in his soundings, its bed is probably
two hundred and fifty feet below the level of the sea. The walls of the
defile rise from eighty to one hundred and fifty feet above the river,
and the strata are inclined to the W.N.W., at an angle of seventy or
eighty degrees. It is worthy of remark, that the course of the river
through this chasm is E.N.E., and that just above the eastern mountain
of the rapid it runs about W.S.W. through the sandstone strata, as if it
had found natural rents by which to make its escape through the ridge of
hills which cross its course here. Similar elbows occur in various parts
of the River, and they may be almost always traced to some peculiarity
in the disposition of the hills which traverse the country.

Captain Franklin gathered many specimens of the limestone strata of the
Ramparts, which are specified in a note.[37] [Sidenote: 148, 149] Some
of the beds at the upper part of the Ramparts consist of a granular
foliated limestone, which was not noticed elsewhere on the banks of the
river, but the greater part are of limestone, strongly resembling that
which has bee