CHAPTER X.

Sketch of the Geological Features of some of the Northern Districts of America.

Frozen Subsoil of Hudson's Bay-Primitive Rocks of Hayes RiverHill River-Borders of Knee Lake-Remarkable Rock-island of Mag'netic Iron Ore-Lake Winipeg-Limestone District-Fort Chipewyan -Carp Lake-Gneiss Formation of the Barren Grounds-Transparent Waters of Great Bear Lake-Fort Franklin-Bear Lake River- Lignite Formation of Mackenzie River-Spontaneous Fire-Pipe ClayAlluvial Islands at the Mouth of the Mackenzie-Copper MountainsCoppermine River-Islands of the Arctic Sea-Arctic Shore-Cape Barrow-Galena Point-Moore's Bay-Bankes' Peninsula-Barry's Island-Cape Croker-Point Turnagain-General Occurrence of the New Red Sand-Stone-Hood's River-Wilberforce Falls-Gneiss Formation-General Summary.

THE great extent of country traversed by our over-land adventurers, the dreary continuance of that universal snow, which so long rendered the surface of the earth in many places almost inaccessible, the frequent journeys in canoes, and the difficulties which almost perpetually prevailed in the way of transporting weighty articles, prevented a complete or very satisfactory knowledge being obtained of the geological structure of the Northern Regions of America.* For the reasons stated below, we shall here confine our observations to certain restricted districts in those regions.

Between the fifty-sixth and fifty-eighth parallels the western shores of Hudson's Bay are extremely flat, and the depth of water decreases very gradually on approaching

*In the fourteenth volume of the Family Library, entitled "Narrative of Discovery and Adventure in the Polar Seas and Regions," the reader will find a chapter on Arctic Geology by Professor Jameson, in which the characteristic formations of Cherie Island, Jan Mayen's Island, Spitzbergen, Old Greenland, and the various insular and continental shores explored by the expeditions under Captains Ross and Parry, are described and commented on. So far, therefore, as regards many of the great North-eastern regions of America, we beg to refer the reader to Professor Jameson's skilful summary. See also observations on the Rock Specimens collected during the First Polar Voyage, by Charles Konig, Esq. Supplement to the Appendix, p. 247.

them. Dr. Richardson states that in seven fathoms of water the tops of the trees are just visible from a ship's deck. Large boulder-stones are scattered over the beach, and sometimes form shoals as far as five miles from shore. These are, of course, troublesome and dangerous to boats. Hayes and Nelson Rivers enter Hudson's Bay about the central portion of this quarter. They are separated on reaching the coast merely by a low alluvial point of land, on which York Factory is stationed. A low and uniformly swampy aspect characterizes the surrounding country and the banks of Hayes River at least for fifty miles inland. The upper soil presents a thin stratum of half-decayed mosses, immediately under which we find a thick bed of tenacious and somewhat slaty bluish clay containing boulderstones. Forests, consisting chiefly of spruces, larches, and poplars, occur, but the individual trees, except under local circumstances of a favourable nature, are of a small size.

The subsoil is generally frozen, and as it consequently retains a great deal of the surface-water, swamps of sphagna and other mosses are always being formed; but the bright summer days, though long, are few, and as vegetation thus decays but slowly, little peat occurs. During a favourable season the ground thaws to the depth of about four feet; but there still remains, it is said, a frozen bed of ten or eleven feet, beneath which we find loose sand. As the earth is not thus permanently frozen in the interior countries of North America, the ungenial condition of the soil about York Factory ought probably to be attributed to the neighbourhood of the sea, which is too much encumbered with ice during winter to mitigate the severity of those naturally frost-bound regions, and being laden along shore with numerous icebergs and other insulated masses, even to the middle of August, must of course diminish the intensity of the summer heat.*

The boulder-stones just mentioned show that there occur in the district of Hayes River several primitive rocks, such as red granite, hornblende rock, gneiss, and syenite; of the transition class, graywacke; and of the secondary class, red sandstone, belonging probably to the new red sandstone

* Appendix to Franklin's First Journey to the Shores of the Polar Sea, p. 499.

formation, in which is included the rothegende and variegated sandstone. Two kinds of limestone likewise occur in this district.

The banks of Steel River, the principal branch of the Hayes, present the same general characters as those of the stream into which it flows. The same may be said of Fox and Hill Rivers, the union of which forms the Steel River. However, on the lower parts of Hill River the banks are more varied in their outlines, and rising more precipitately and from a narrow channel, they attain to an elevation of nearly 200 feet. About a mile below the Rock Portage, that is, about 100 miles from the sea, rocks first occur in situ. They consist of gneiss, and rise in the channel of the river from beneath lofty banks of clay. This gneiss formation seems to extend to Lake Winipeg, and contains subordinate beds and veins of granite, and beds of hornblende rock, and mica-slate. At the Swampy Portage a bed of red felspar occurs. It contains small grains of epidote, and at the Upper Portage hornblende-slate was observed, alternating with gray gneiss, slightly intermingled with hornblende, together with beds of quartz rock containing precious garnets. At the Lower Portage on Jack River (the name of Hill River after crossing Swampy Lake) a red granite occurs. The rocks on Jack River are low, with a very spare covering of soil; the woods are thin, and the surrounding country flat. The borders of Knee Lake present similar characters; but in one spot which was examined on account of its exhibiting a more luxuriant growth of trees, the soil was still thin, but the subjacent rock consisted of primitive greenstone, with disseminated iron pyrites. "About half a mile from the bend or knee of the lake," says Sir John Franklin, "there is a small rocky island, composed of magnetic iron ore, which affects the magnetic needle at a considerable distance. Having received previous information respecting this circumstance, we watched our compasses carefully, and perceived that they were affected at the distance of three hundred yards, both on the approach to and departure from the rock on decreasing the distance they became gradually more and more unsteady, and on landing they were rendered useless; and it was evident that the general magnetic influence was totally overpowered by the local attraction of the ore,

When Kater's compass was held near to the ground, on the north-west side of the island, the needle dipped so much that the card could not be made to traverse by any adjustment of the hand; but on moving the same compass about thirty yards to the west part of the islet, the needle became horizontal, traversed freely, and pointed to the magnetic north."*

We are indebted to Sir Alexander Mackenzie for the valuable observation, that the principal lakes in these northern quarters are interposed between the primitive rocks and the secondary strata which lie to the westward of them. Of this Lake Winipeg affords a good example. It is a long narrow sheet of water, bounded on its eastern side by primitive rocks, which are mostly granitic, while horizontal limestone strata form its more indented western shore.

The north shore of Lake Winipeg is formed into a peninsula by Play-Green Lake and Limestone Bay. Steep cliffs of clay are here prevalent, similar to those which preceded the gneiss in Hill River, but containing rather more calcareous matter. The beach is composed of calcareous sand, and fragments of water-worn limestone, of which there are two kinds; the one yellowish-white, dull, with conchoidal fracture and translucent edges; the other bluish and yellowish-gray, dull, with an earthy fracture and opaque. Dr. Richardson did not observe any rocks of the former kind in situ in this neighbourhood, although cliffs of the latter were apparent on the west side of Limestone Bay, and continued to bound the lake as far as the mouth of the Saskatchawan, and were reported to spread down the whole of its western shore.

The extension of the limestone deposites of Lake Winipeg, in a westerly direction, has not been ascertained, but it has been traced as far up the Saskatchawan as Carlton House, where it is at least 280 miles in breadth.

This limestone extends over a vast tract of country, and may in general be characterized as compact, splinty, and yellowish-gray. It is very testaceous, and large portions of it are entirely composed of bivalve shells. In the journey up the Saskatchawan it was traced to the Neepewan, a distance of 300 miles, where it is either succeeded or covered

*Journey to the Shores of the Polar Sea, p. 36,

by cliffs of calcareous clay. It is probable that the limestone formation not only extends over a vast portion of the plains, but also runs parallel to the Rocky Mountains as far as Mackenzie River. Between it and the Rocky Mountains, rocks of the coal formation occur; and beds of burning coal have been known for many years on the upper parts of the Saskatchawan, as well as on the last-named river. One of the most marked characteristics of the limestone formation is the entire exclusion of foreign beds. It was never observed in association with any other rock, except, perhaps, on Elk River, where it appeared in contact with compact earthy marl and slaggy mineral-pitch, or bituminous sandstone; and on Coppermine River, where rolled fragments of a similar stone were found connected with layers of dark flinty slate. Salt springs and lakes exist from twelve to twenty miles to the northward of Carlton House.

In Athabasca Lake Sir John Franklin's party came again upon the edge of the primitive formation. Fort Chipewyan seemed to stand upon a granite rock, and a little to the eastward a reddish granite is associated with gray gneiss. Granite is the most abundant rock on Slave River; but it disappears about a mile and a half below the Portage des Noyes, and the banks from thence to Slave Lake are alluvial. At the mouth of the Yellow Knife River, and in Lake Prosperous, mica-slate prevailed; and between Rocky and Carp Lakes the granite contains many beds of mica-slate, often passing into clay-slate. Here the country is tolerably wooded, and white spruce occupy the rocky situations, Pinus Banksiana the sandy spots, and aspen the low moist places.

*

At Carp Lake the hills are of lower altitude, the valleys are less fertile and have fewer trees, and these features seem to characterize the commencement of the gneiss formation, which extends over the great district to the eastward of the Coppermine River, termed by the Indians the Barren Grounds. The soil is inimical to almost every species of vegetation. The summits of the hills about Fort Enterprise are composed of a durable red granite, and large masses of the same substance are scattered over their surface. Оп

Appendix to Franklin's First Journey to the Shores of the Polar Sea, p. 520.