Читать книгу The Ipswich Sparrow and Its Summer Home - Jonathan Jr. Dwight - Страница 5

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The geologists tell us Sable Island is either the remains of a sand continent of remote glacial origin or, more probably, a vast heap of glacial detritus brought from the north by the ice-floes of a more modern period and heaped up by existing ocean currents.^[7] At all events, it now forms the ribbon-like crest of a submerged bank two hundred miles long by ninety in breadth, similar to those extending from Newfoundland to the shoals of Nantucket. A scant twenty miles of rolling sand-hills is all that remains today above the surface of the ocean, some of the sand mountains attaining an elevation of eighty feet and resembling in almost every particular save greater size the stretches of sand dunes to be found along our Atlantic seaboard,—the same treeless aspect, the same sparse covering of coarse beach-grass, the same deserts of shifting white sand. But on Sable Island in the hollows among the hills and often to their very summits, grasses grow luxuriantly in many places, and a large part is carpeted with the evergreen Crowberry (Empetrum nigrum L.) and Juniper (Juniperus nana Willd.) which are very characteristic productions. Between the two lighthouses it stretches in the form of a slender crescent, the concavity towards the Nova Scotia coast distant at its nearest point eighty-six geographical miles. The horns of the crescent extend at either end in several parallel submerged bars a distance of fifteen miles or more, where vessels have been lost a dozen miles from the nearest land. About a mile of grassy sand-hills now intervenes between each light and the northeast and northwest bars respectively. The former dries for several miles at low tide in fine weather, but the latter only shows little patches of damp sand, the remains of what was once part of the island; and if you stand at the western extremity, the sand is actually eaten away from beneath your very feet by a swift current from the southeast. As far as the eye can reach, an imposing white line of breaking surf extends out on both the bars.

The greatest width of the island hardly anywhere exceeds a mile, and a lagoon called Lake Wallace, or simply ‘the lake,’ stretching along more than one half of its length, diminishes the land area of the western portion fully one half. The lake, at most a few hundred yards in width and very shallow, is separated from the ocean southward by a bare sand-bar over which the sea breaks in time of storm and through which it has forced two narrow inlets. As we have seen, not many years ago this ‘south beach,’ as it is called, was a substantial barrier of grassy sand-hillocks. Between the lake and the ocean northward intervenes a backbone of hillocks that increase in size eastward, until they culminate in a huge continuous bank. This maintains, almost without a break for six or eight miles, an elevation of sixty to eighty feet. Viewed in the fog it looms up like an important range of mountains, descending abruptly on the ocean side, and sloping more gradually into the central valleys of the island, which are blocked at every turn with lesser hills and diversified with numerous fresh-water ponds. A less impressive southern range of hills extends along the shore eastward from the foot of the lake. The wind has carved them into numberless peaks, and here as well as in many other places its resistless force is shown.

Once let a ‘raw’ spot (as it is aptly called) be found,—a break perhaps by hoofs of cattle in the grassy hillside,—and soon a hollow is whirled out that succeeding storms convert into a great gully or channel through the hills, over the steep sides of which hangs a feathery curtain of tangled roots and grass, vainly endeavoring to shield the edges from further injury. From one end to the other the island is a series of startling contrasts, verdure and sand desert going hand in hand. A single winter’s storm may completely change the face of the landscape, spiriting away hillocks in this place, building up others in that, and spreading a thick blanket of sand over what was perhaps the fairest spot of all. This burying process produces the thin layers of vegetable mould that alternate in many places with the sand of which the soil is almost wholly composed. The sand consists chiefly of fine rounded grains of white or transparent quartz, and no stones are found.^[8] The beach is strewn with shells of many species, and its monotonous stretches are relieved by the ribs and other fragments of unfortunate vessels. Inland, the continuous areas of vegetation are much more extensive over the eastern half of the island than elsewhere; and evergreen shrubs almost entirely replace the turf-covered areas of its western part.