Sketch of the Geology of the Arctic Regions. 5 
On the banks of the McKenzie below Bear Lake River, are pre- 
cipitous cliffs of bituminous shale, and near it, and in most instances 
underlying it, are horizontal strata of limestone. Salt springs are 
connected with this formation. 'The Rocky Mountains appear at 
no great distance from the McKenzie at the rapids in that river, where 
limestone ridges traverse the country. Pieces of chert and frag- 
ments of trap rock, connected by cale spar, and immediatly below, 
horizontal strata of sandstone, form the banks and bed of the river. 
Forty miles below the first rapid, the sides of the river rise into mural 
precipices of limestone, ‘weathered into columns,” and castellated 
towers. Marly stones, containing corallines, accompany these rocks. 
At this remarkable “ Rapid” called by the traders “the Ram 
according to McKenzie, the river is narrowed to three hundred yards, 
with fifty fathoms depth of water, and the defile is three miles in length. 
The banks rise on each side of this tremendous chasm, from eighty 
to a hundred feet above the level of the river. The ledges and cliffs 
of “the Ramparts,” are of foliated granular limestone, stained with 
bitumen, and accompanying the river through this astonishing gorge, 
limestones of every variety appear, in some places associated with 
carbonaceous matters ; in others with corallines and fossil shells, clay 
and marly deposits. Below “the Ramparts” the river expands to 
the breadth of two miles, and its banks slope away to a moderate 
elevation. 
In latitude 66°, perpendicular hills of sandstone a hundred and six- 
ty feet high, containing coarse grained quartz, repose in horizontal 
strata, upon horizontal limestone. The sandstone cliffs present many 
imbedded minerals, such as translucent quartz; black lydian stone ; 
and disintegrated felspar. ‘The underlying beds of limestone con- 
tain many shells and chain coral, traversed by veins of calc spar. 
Forty miles below these sandstone walls and hills, marl slate 
breaking into shelving acclivities, and deep ravines, forms the banks 
of the river, which again contracting gives to this reach, for twenty 
miles, the name of “the Narrows.” On emerging from “the Nar- 
rows,” the McKenzie forms a number of deltas through which it falls 
into the sea. The Rocky Mountains form the western boundary of 
the lowlands of the deltas, and the Reindeer hills a parallel bounda- 
ry on the eastern side. Limestone occurs in conical knolls, but a 
loose sandstone predominates. The sandstone contains black flinty 
slate, or lydian stone, and white quartz, accompanied by acclivities 
of sand. The summits of the hill are thinly coated with coarse peb- 
