After passing Sellwood Bay, the north and east shores of Cape Parry, and the islands skirting them, present magnificent cliffs of limestone, which, from the weathering action of the waves of the sea, assume 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 passage 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.
208, 209The 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.
214Near the extremity of Cape Lyon the slate-clay predominates, occurring in straight, thin, bluish-gray layers, which are interspersed with detached scales of mica. 215It 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 altitude 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 grasses and carices exists at Cape Lyon, than is usual on those shores. 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°. 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 quantity 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.
At Point De Witt Clinton, a compact blackish-blue limestone, traversed by veins of calc-spar, forms a bed thirty feet thick,217
218
219 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 accumulations 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° 20', 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.