Some of these specimens contain corallines and terebratulae; and at the lower end of the defile there are horizontal strata of limestone, covered by a thin layer of flinty slate.
Below the _ramparts_ the river expands to the width of two miles, and for a reach or two its banks are less elevated. In lat. 66-3/4 degrees, about thirty miles from the ramparts, there are cliffs which Captain Franklin in his notes, remarks, "run on an E. by S. course for four miles, are almost perpendicular, about one hundred and sixty feet high, and present the same castellated appearances that are exhibited by the sandstone above the defile of the "ramparts." [Sidenote: 159, 160, 161, 162] The cliffs[38] are, in fact, composed of sandstones similar, in general appearance, to those which occur higher up the river; but some of the beds contain the quartz in coa.r.s.er grains, with little or no cement. [Sidenote: 163, 164, 165, 166] The beds are horizontal, and repose on horizontal limestone,[39] from which Captain Franklin broke many specimens in 1825. [Sidenote: 167, 168, 169, 170] We landed at this place in 1826 to see the junction of the two rocks, but the limestone was concealed by the high waters of the river. Captain Franklin"s specimens are full of sh.e.l.ls, many of which are identical with those of the flat limestone strata of the Athabasca River. [Sidenote: 171] One bed appears to be almost entirely composed of a fine large species of terebratula, not yet described, but of which Mr. Sowerby has a specimen from the carboniferous limestone of Neho, in Norway. Some of the beds contain the sh.e.l.ls in fragments; in others, the sh.e.l.ls are very entire.
About forty miles below these sandstone walls the banks of the river are composed of marl-slate, which weathers so readily, that it forms shelving acclivities. [Sidenote: 172] In one reach the soft strata are cut by ravines into very regular forms, resembling piles of cannon shot in an a.r.s.enal, whence it was named _Shot-reach_.
The river makes a short turn to the north below Shot Reach, and a more considerable one to the westward, in pa.s.sing the present site of Fort Good Hope. The banks in that neighbourhood are mostly of clay, but beds of sandstone occasionally show themselves. The Indians travel from Fort Good Hope nearly due north, reach the summit of a ridge of land 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 sh.o.r.es 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-b.u.t.ter, 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 pa.s.sing 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 pa.s.s 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 pa.s.sage 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. [Sidenotes: 180, 181, 182] They are parted by thin slaty beds of sandstone, containing small pieces apparently of bituminous coal, and some casts of vegetables. [Sidenote: 183] Most of the beds contain scales of mica, and some of them have nodules of indurated iron-shot clay which exhibit obscure impressions of sh.e.l.ls. A bed of imperfectly crystalline limestone was seen by Captain Franklin underlying the sandstones.
MACKENZIE RIVER BELOW "THE NARROWS."
The Mackenzie, on emerging from the Narrows, separates into many branches, which flow to the sea through alluvial or diluvial deltas and islands. The Rocky Mountains are seen on the western bank of the river, forming the boundary of those low lands; and the lower, but decided ridge, of the Rein-deer Hills holds nearly a parallel course on the east bank. The estuary lying between these two ranges, opens to the N.W. by N. into the Arctic Sea. I have already mentioned the specimens of rocks obtained at the few points of the Rocky Mountains that were visited,[42]
and therefore shall now speak only of the Rein-deer Hills. We did not approach them until we had pa.s.sed for thirty miles down a branch of the river which winds through alluvial lands. At this place there are several conical hills about two hundred feet high, which appeared to consist of limestone. Specimens taken from some slightly-inclined beds near their bases, consisted of a fine-grained, dark, bluish-gray limestone. After pa.s.sing these limestone rocks, the Rein-deer Hills were pretty uniform in appearance, having a steep acclivity with rounded summits. Their height, on the borders of the river, is about four hundred feet, but a mile or two inland they attain an elevation of perhaps two hundred feet more. Their sides are deeply covered with sand and clay, arising most probably from the disintegration of the subjacent rocks. [Sidenote: 184, 185] A section made by a torrent, showed the summit of one of the hills to be formed of gray slate-clay, its middle of friable gray sandstone much iron-shot, and its base of dark bluish-gray slaty clay. The sandstone predominates in some parts of the range, forming small cliffs, underneath which there are steep acclivities of sand. It contains nearly an equal quant.i.ty of black flinty slate, or lydian stone, and white quartz in its composition, and greatly resembles the friable sandstones of the lignite formation at the mouth of Bear Lake River. [Sidenote: 186] In some parts the soil has a red colour from the disintegration of a reddish-brown slate-clay.
[Sidenote: 187] The summits of the hills that were visited were thinly coated with loose gravel, composed of smooth pebbles of lydian-stone, intermixed with some pieces of green felspar, white quartz, limestone, and chert. In some places almost all the pebbles were as large as a goose-egg, in others none of them exceeded the size of a hazel nut. The Rein-deer Mountains terminate in lat. 69 degrees, having previously diminished in alt.i.tude to two hundred feet, and the eastern branch of the river turns round their northern extremity. White spruce trees grow at the base of these hills as far as lat. 68-1/2 degrees; north of which they become very stunted and straggling, and very soon disappear, none reaching to lat. 69 degrees.
Sir Alexander Mackenzie, who, on his return from the sea, walked over these hills, says, "Though the country is so elevated, it is one continued mora.s.s, except on the summits of some barren hills. As I carried my hanger in my hand, I frequently examined if any part of the ground was in a state of thaw, but could never force the blade into it beyond the depth of six or eight inches. The face of the high land towards the river is, in some places, rocky, and in others a mixture of sand and stone, veined with a kind of red earth, with which the natives bedaub themselves." It was on the 14th of July that he made these observations. On the 5th of the same month, in a milder year, we found that the thaw had penetrated nearly a foot into the beds of clay at the base of the hills.
ALLUVIAL ISLANDS AT THE MOUTH OF THE MACKENZIE.
The s.p.a.ce between the Rocky Mountains and Rein-deer Hills, ninety miles in length from lat. 67 degrees 40 minutes to 69 degrees 10 minutes, and from fifteen to forty miles in width, is occupied by flat alluvial islands, which separate the various branches of the river. Most of these islands are partially or entirely flooded in the spring, and have their centres depressed and marshy, or occupied by a lake; whilst their borders are higher and well clothed by white spruce trees. The spring floods find their way, through openings in these higher banks, into the hollow centres of the islands, carrying with them a vast quant.i.ty of drift timber, which, being left there, becomes water-soaked, and, finally, firmly impacted in the mud. The young willows, which spring up rapidly, contribute much towards raising the borders of the stream, by intercepting the drift sand which the wind sweeps from the margin of the shallow ponds as they dry up in summer. The banks, being firmly frozen in spring, are enabled to resist the weight of the temporary floods which occur in that season, and before they are thawed the river has resumed its low summer level. The trees which grow on the islands terminate suddenly, in lat. 68 degrees 40 minutes.
I have already mentioned, that a large sheet of brackish water, named Esquimaux Lake, lies to the eastward of the Rein-deer Mountains, running to the southward, and approaching within sixty miles of the bend of Mackenzie"s River at Fort Good Hope. This lake has a large outlet into Liverpool Bay, to the westward of Cape Bathurst, and there are many smaller openings betwixt that bay and Point Encounter, near the north end of the Rein-deer Hills, which are also supposed to form communications betwixt the lake and the sea. The whole coast-line from Cape Bathurst to the mouth of the Mackenzie, and the islands skirting it, as far as Garry and Sacred Islands, present a great similarity in outline and structure. They consist of extensive sandy flats, from which there arise, abruptly, hills of an obtuse conical form, from one to two hundred feet above the general level. Sandy shoals skirt the coast, and numerous inlets and basins of water divide the flat lands, and frequently produce escarpments of the hills, which show them to be composed of strata of sand of various colours, sometimes inclosing very large logs of drift timber. There is a coating of black vegetable earth, from six inches to a foot in thickness, covering these sandy hummocks, and some of the escarped sides appeared black, which was probably caused by soil washed from the summit.
It is possible that the whole of these eminences may, at some distant period, have been formed by the drifting of moveable sands. At present the highest floods reach only to their bases, their height being marked by a thick layer of drift timber. When the timber has been thrown up beyond the reach of ordinary floods, it is covered with sand, and, in process of time, with vegetable mould. The _Elymus mollis_, and some similar gra.s.ses with long fibrous roots, serve to prevent the sand-hills from drifting away again. Some of the islands, however, consist of mud or clay. Captain Franklin describes Garry"s Island as presenting cliffs, two hundred feet high, of black mud, in which there were inclined beds of lignite. [Sidenote: 188] Specimens of this lignite have the same appearance with the fibrous wood-coal occurring in the formation at the mouth of Bear Lake River, and, like it, contain resin. [Sidenotes: 189, 190] Imbedded in the same bank, there were large ma.s.ses of a dark-brown calc-tuff, full of cavities containing some greenish earthy substance.
Some boulders of lydian stone strew the beach. The cliffs of Nicholson"s Island also consisted of sand and mud, which, at the time of our visit, (July 16th,) had thawed to the depth of three feet. This island rises four hundred feet above the level of the sea, and is covered with a thin sward of gra.s.ses and bents.
SEA-COAST.--BITUMINOUS ALUM SHALE.
The main land to the east of Nicholson"s Island, as far as Cape Bathurst, presents gently swelling hills, which attain the height of two hundred feet at the distance of two miles from the beach, and the ground is covered with a sward of moss and gra.s.ses. At Point Sir Peregrine Maitland there are cliffs forty-feet high of sand and slaty clay, and the ravines are lined with fragments of whitish compact limestone, exactly resembling that which occurs in Lakes Huron and Winipeg, and which was afterwards seen forming the promontory of Cape Parry, bearing E.N.E. from this place. The beach, on the south side of Harrowby Bay, not far from Point Maitland, was thickly strewed with fragments of dark red and of white sandstone, together with some blocks of the above-mentioned limestone, and a few boulders of sienite.
From Cape Bathurst the coast line has a S.E. direction, and is formed by precipitous cliffs, which gradually rise in height from thirty feet to six hundred. The beds composing these cliffs appear to be a.n.a.logous to those of the alum-shale banks at Whitby, and similar to those which skirt the Scented-gra.s.s Hill and Great Bear Mountain, in Great Bear Lake. The Scented-gra.s.s Hill is distant from Cape Bathurst about three hundred miles, on a S.E. bearing, which corresponds, within a point, with the direction of the princ.i.p.al mountain chains in the country.
[Sidenote: 191] There is evidently a striking similarity in the form of the ground plan of these two promontories. At the extremity of Cape Bathurst the cliffs consist of slaty-clay, which, when dry, has a light bluish-gray colour, a slightly greasy feel, and falls down in flakes.
The rain-water had penetrated the cliff to the depth of three yards from the summit; and this portion was frozen, on the 17th July, into an icy wall, which crumbled down as it thawed. On proceeding a little further along the coast, some beds were observed that possessed, when newly exposed to the air, tenacity enough to be denominated stone, but which, under the action of water, speedily softened into a tenacious bluish-clay.
[Sidenotes: 192, 193, 197, 198, 199] At Point Traill we were attracted by the variegated colours of the cliff, and on landing found that they proceeded from clays baked by the heat of a bed of bituminous-alum-shale which had been on fire. Some parts of the earth were still warm. The shale is of a brown colour and thin slaty structure, with an earthy fracture. It contains many interspersed crystals of selenite; between its lamina there is much powdery alum, mixed with sulphur, and it is traversed by veins of brown selenite, in slender prismatic crystals.
[Sidenotes: 200, 194, 195, 196] The bed was much broken down, and hid by the debris of the bank, but in parts it was several yards thick, and contained layers of the wax-coloured variety of alum, named Rock-b.u.t.ter.
The shale is covered by a bed of stone, chiefly composed of oval distinct concretions of a poor calcareous clay-iron stone. These concretions have a straight cleavage in the direction of their short axis, and are often coated by fibrous calc-sinter and calcedony. The upper part of the cliff is clay and sand pa.s.sing into a loosely cohering sandstone. The strata are horizontal, except in the neighbourhood of ravines, or of consumed shale, when they are often highly inclined, apparently from partial subsidence. The debris of the cliff form declivities, having an inclination of from fifty to eighty degrees, and the burnt clays variously coloured, yellow, white, and deep red, give it much the appearance of the rubbish of a brick-field. The view of the interior, from the summit of the cliff, presents a surface slightly varied by eminences, which swell gently to the height of fifty or sixty feet above the general level. The soil is clayey, with a very scanty vegetation, and there are many small lakes in the country.
[Sidenote: 201] Ten miles further on, the alum-shale forms a cliff two hundred feet high, and presents layers of the Rock-b.u.t.ter about two inches thick, with many crystals of selenite on the surfaces of the slates. The summit of the cliff consists of a bed of marly gravel two yards thick, which is composed of pebbles of granite, sienite, quartz, lydian-stone, and compact limestone, all coated by a white powdery marl.
The dip of the strata at this place is slightly to the northward.
A few miles to the south-east of Wilmot Horton River the cliffs are six hundred feet high, and present acclivities having an inclination of from thirty to sixty degrees, formed of weathered slate-clay. Some beds of alum-shale are visible at the foot of these cliffs, containing much sulphate of alumina and ma.s.ses of baked clay.
Two miles further along the coast the shaly strata were on fire, giving out smoke, and beyond this the cliffs become much broken but less precipitous, having fallen down in consequence of the consumption of the combustible strata. These ruined cliffs gradually terminated in green and sloping banks, whose summit was from one to two miles inland, and about six hundred feet above the sea level. Considerable tracts of level ground occurred occasionally betwixt these banks and the beach. Wherever the ground was cut by ravines, beds of slate-clay were exposed. On reaching the bottom of Franklin Bay, we observed the higher grounds keeping an E.S.E. direction until lost to the view, becoming, however, somewhat peaked in the outline.
SEA COAST.--LIMESTONE.
Parry"s Peninsula, where it joins the mainland, is very low, consisting mostly of gravel and sand, and is there greatly indented by shallow bays, but it gradually increases in height towards Cape Parry. The bays and inlets are separated from the sea by beaches composed of rolled pieces of compact limestone; and which, although they are in places only a few yards across, are several miles in length. The northern part of Parry"s Peninsula belongs entirely to a formation which appears from the mineralogical characters of the stone composing the great ma.s.s of the strata, and the organic remains observed in it, to be identical with the limestone formations of Lakes Winipeg and Huron.
[Sidenotes: 202, 204] On the north side of Sellwood Bay, in lat. 69 degrees 42 minutes, cliffs about twenty feet high are composed of a fine-grained[43] brownish dolomite, in angular distinct concretions, and containing corallines and veins of calc-spar. [Sidenote: 203] In the same neighbourhood there is a bed of grayish-black compact luculite with drusses of calc-spar, very similar to the limestone which occurs in highly inclined strata at the "Rock by the River Side," on the Mackenzie, and in horizontal strata in an island near that rock, where it forms angular concretions.
After pa.s.sing Sellwood Bay, the north and east sh.o.r.es of Cape Parry, and the islands skirting them, present magnificent cliffs of limestone, which, from the weathering action of the waves of the sea, a.s.sume curious architectural forms. Many of the insulated rocks are perforated.
Between the bold projecting cliffs of limestone there are narrow shelving beaches, formed of its debris, that afford access to the interior. The strata have generally a slight dip to the northward, and the most common Rock is a yellowish-gray dolomite which has a very compact structure, but presents some shining facets of disseminated calc-spar. This stone, which is not to be distinguished by its mineralogical characters from the prevailing limestone of Lake Winipeg, and at the pa.s.sage of _La cloche_ in Lake Huron, forms beds six or eight feet thick, and is frequently interstratified with a cellular limestone, approaching to chert in hardness, and exhibiting the characters of rauchwacke. In some parts, the rauchwacke is the predominating rock, and has its cells beautifully powdered with crystals of quartz or of calc-spar, and contains layers of chert of a milky colour. The chert has sometimes the appearance of calcedony, and is finely striped.
[Sidenote: 208, 209] The extremity of Cape Parry is a hill about seven hundred feet high, in which beds of brownish dolomite, impregnated with silica, are interstratified with a thin-slaty, gray limestone, having a compact structure.[44] The vegetation is very scanty, and there are some spots covered with fragments of dolomite, on which there is not the vestige even of a lichen. Many large boulders of greenstone were thrown upon the N.W. point of Cape Parry. The islands in Darnley Bay, between Capes Parry and Lyon, are composed of limestone.
SEA-COAST.--FORMATION OF SLATE-CLAY, SANDSTONE, AND LIMESTONE, WITH TRAP-ROCKS.
From Cape Lyon to Point Tinney, the rocks forming the coast-line are slate-clay, limestone, greenstone, sandstone, and calcareous puddingstone.
[Sidenote: 214] Near the extremity of Cape Lyon the _slate-clay_ predominates, occurring in straight, thin, bluish-gray layers, which are interspersed with detached scales of mica. [Sidenote: 215] It sometimes forms thicker slates, that are impregnated with iron, and occurs alone, or interstratified in thin beds with a reddish, small-grained limestone.
The strata, in general, dip slightly to the N.E., and form gently-swelling grounds, which at the distance of about fifteen miles to the southward terminate in hills, named the Melville Range. These hills are apparently connected with those which skirt the coast to the westward of Parry"s Peninsula, have rather a soft outline, and do not appear to attain an alt.i.tude of more than seven or eight hundred feet above the sea. Ridges of naked trap-rocks, which traverse the lower country betwixt the Melville hills and the extremity of the Cape, rise abruptly to the height of one hundred or one hundred and fifty feet, and have, in general, an E.N.E. direction. When these trap ridges reach the coast, they form precipices which frequently have a columnar structure, and the nearly horizontal strata of slate-clay are generally seen underlying the precipices. In many places the softer clay strata are worn considerably away, and the columns of greenstone hang over the beach. Columns of this description occur at the north-eastern extremity of the Cape, and the slate-clay is not altered at its point of contact with the greenstone. The soil in this neighbourhood is clayey, and some small streams have pretty lofty and steep clayey banks; the shaly strata appearing only at their base. A better sward of gra.s.ses and carices exists at Cape Lyon, than is usual on those sh.o.r.es. Many boulders of greenstone and large fragments of red sandstone strew the beach.
At Point Pearce, four or five miles to the eastward of Cape Lyon, a reddish, small-grained limestone forms perpendicular cliffs two hundred feet high, in which a remarkable cavern occurs. Near these cliffs the slate-clay and reddish limestone are interstratified, and form a bold rocky point, in which the strata dip to the N.E. at an angle of 20 degrees. The coast line becomes lower to the eastward, and at Point Keats a fine-grained, flesh-coloured sandstone occurs. This sandstone is quartzose, does not possess much tenacity, and is without any apparent basis.
At Point Deas Thompson the limestone re-appears, having reddish-brown and flesh-red colours, and a splintery fracture. There are some beautiful Gothic arches formed in the cliffs there by the weathering of the strata.
Five miles farther along the coast, near Roscoe River, the same kind of limestone forms cliffs twenty-five feet high, and is covered by thin layers of soft slate-clay. On the top of these cliffs we observed a considerable quant.i.ty of drift-timber and some hummocks of gravel. The spring tides do not rise above two feet. The Melville Range approaches within three miles of the coast there, and presents a few short conical summits, although the hills composing it are mostly round-backed.
[Sidenotes: 217, 218, 219] At Point De Witt Clinton, a compact blackish-blue limestone, traversed by veins of calc-spar, forms a bed thirty feet thick, which reposes on thin layers of a soft, compact, light, bluish-gray limestone or marl. The cliffs at this place are altogether about seventy feet high, but their bases were concealed by acc.u.mulations of ice. Veins filled with compact and fibrous gypsum traverse the upper limestone. Naked and barren ridges of greenstone, much iron-shot, cross the country here, in the same manner as at Cape Lyon. The soil consists of gravel and clay; the former mostly composed of whitish magnesian limestone; and the vegetation is very scanty.
At Point Tinney, in lat. 69 degrees 20 minutes, cliffs of a calcareous puddingstone, about forty feet high, extend for a mile along the coast.
The basis, in most of the beds, is calc-spar; but in some small layers it is calcareous sand. The imbedded pebbles are smooth, vary in magnitude, from the size of a pea to that of a man"s hand, and are mostly or entirely of chert, which approaches to calcedony, and, when striped, to agate in its characters. Perhaps, much of the gravel which covers the country is derived from the destruction of this conglomerate rock.
SEA COAST.--LIMESTONE.
From Point Clifton to Cape Hearne, the whole coast consists of a formation of limestone precisely similar to that which occurs on Lake Winipeg and Parry"s Peninsula.
Dolomite, the prevailing rock in this formation, is generally in thin layers, and has a light smoke-gray colour, varying occasionally to yellowish gray, and buff. Its structure is compact, with little l.u.s.tre, except from facets of disseminated calc-spar. It sometimes pa.s.ses into milk-white chert, which forms beds. In some places the dolomite alternates with cellular limestone, which is generally much impregnated with quartz, and has its cavities powdered with crystals of that mineral. No organic remains were observed in the strata, but fragments, evidently derived from some beds of the formation, contained orthocerat.i.tes, like those of Lake Huron. The strata, though nearly horizontal, appear to crop out towards the north and east, forming precipices about ten feet high, facing in that direction, and running like a wall across the country. In many places, however, and particularly at Cape Krusenstern, the strata terminate in magnificent cliffs upwards of two hundred feet high, the country in the interior remaining level. Mount Barrow is a small hill of limestone, of a remarkable form, being a natural fortification surrounded by a moat. The coast line is indented by shallow bays, and skirted by rocks and islands.
In the whole country occupied by this formation, the ground is covered with slaty fragments, sometimes to the depth of three feet or more.
These slates appear to have been detached from the strata they cover, by the freezing of the water, which insinuates itself betwixt their layers.
At Cape Bexley, the fragments of dolomite cover the ground to the exclusion of all other soil; and in a walk of several miles, I did not see the vestige of a vegetable, except a small green sc.u.m upon some stones that formed the lining of a pond which had dried up. In this neighbourhood there are a number of straight furrows a foot deep, as if a plough had been drawn through the loose fragments. After many conjectures as to the cause of this phenomenon, I ascertained that the furrows had their origin in fissures of the strata lying underneath.
At the commencement of this formation between Point Tinney and Point Clifton, the coast is low, and a stream of considerable magnitude, named Croker River, together with many rivulets, flow into the sea. Its termination to the southward of Cape Hearne is also marked by a low coast line, which is bounded by the bold rocky hills of Cape Kendall.
FORMATION SIMILAR TO THAT AT CAPE LYON.