Читать книгу An Expedition to Mount St. Elias, Alaska (Illustrated Edition) - Israel C. Russell - Страница 3

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The southern coast of Alaska is remarkable for the regularity of its general outline. If a circle a thousand miles in diameter be inscribed on a map of the northern Pacific with a point in about latitude 54° and longitude 145° as a center, a large part of its northern periphery will be found to coincide with the southern shore of Alaska between Dixon entrance on the east and the Alaska peninsula on the west. On the northern part of this great coast-circle lies the region explored in the summer of 1890 and described in the following pages.

From Cross sound, at the northern end of the great system of islands forming southeastern Alaska, westward along the base of the Fairweather range, the mountains are exceedingly rugged, and present some of the finest coast scenery in the world. There are but two inlets east of Yakutat bay on this shore which afford shelter even for small boats. These are Lituya bay and Dry bay. Ships may enter Lituya bay, at certain stages of the tide, and find a safe harbor within; but the approaches to Dry bay are not navigable. West of Yakutat bay the coast is equally inhospitable all the way to Prince William sound.

As if to compensate for the lack of refuge on either end, there is in the center of this great stretch of rock-bound coast, over 300 miles in extent, a magnificent inlet known as Yakutat bay, in which a thousand ships could find safe anchorage. On some old maps this bay is designated as "Baie de Monti," "Admiralty bay" and "Bering bay," as will be seen when its discovery and history are discussed on another page.

The southern shore of Alaska, for a distance of 200 miles along the bases of the Fairweather and St. Elias ranges, is formed of a low table-land intervening between the mountains and the sea. Yakutat bay is the only bight in this plateau sufficiently deep to reach the mountain to the northward. This bay has a broad opening to the sea; the distance between its ocean capes is twenty miles, and its extension inland is about the same. Its eastern shore is fringed with low, wooded islands, among which are sheltered harbors, safe from every wind that blows. The most accessible of these is Port Mulgrave, near its entrance on the eastern side.

The shores of Yakutat bay, on both the east and the west, are low and densely wooded for a distance of twenty-five miles from the ocean, where the foot-hills of the mountains begin. At the head of the bay the land rises in steep bluffs and forms picturesque mountains, snow-capped the year round. These highlands, although truly mountainous in their proportions, are but the foot-hills of still nobler uplifts immediately northward. The bay extends through an opening in the first range to the base of the white peaks beyond. This opening was examined a century ago by explorers in search of the delusive "Northwest passage," in the hope that it would lead to the long-sought "Strait of Annan"—the dream of many voyagers. It was surveyed by the expedition in command of Malaspina in 1792, and on account of his frustrated hopes was named "Puerto del Desengaño," or "Disenchantment bay," as it has been rendered by English writers.

The waters of Yakutat and Disenchantment bays are deep, and broken only by islands and reefs along their eastern shores. A few soundings made in Disenchantment bay within half a mile of the land showed a depth of from 40 to 120 fathoms. The swell of the ocean is felt up to the very head of the inlet, indicating, as was remarked to me by Captain C. L. Hooper, that there are no bars or reefs to break the force of the incoming swells.

The lowlands bordering Yakutat bay on the southeast are composed of assorted glacial débris. Much of the country is low and swampy, and is reported to contain numerous lakelets. Northwest of the bay the plateau is higher than toward the southeast, and has a general elevation of about 500 feet at a distance of a mile from the shore; but the height increases toward the interior, where a general elevation of 1,500 feet is attained over large areas. All of this plateau, excepting a narrow fringe along the shore, is formed by a great glacier, belonging to what is termed in this paper the Piedmont type. There are many reasons for believing that the plateau southeast of Yakutat bay was at one time covered by a glacier similar to the one now existing on the northwest.1

The mountains on the northern border of the seaward-stretching table-lands, both southeast and northwest of Yakutat bay, are abrupt and present steep southward-facing bluffs. This escarpment is formed of stratified sandstones and shales, and owes its origin to the upheaval of the rocks along a line of fracture. In other words, it is a gigantic fault scarp. The gravel and bowlders forming the plateau extending oceanward have been accumulating on a depressed orographic block (or mass of strata moved as a unit by mountain-making forces), which has undergone some movement in very recent times, as is recorded by a terrace on the fault scarp bordering it. West of Yakutat the geological structure is more complex, and long mountain spurs project into the platform of ice skirting the ocean. Filling the valleys between the mountain spurs, there are many large seaward-flowing glaciers, tributary to the great Piedmont ice-sheet.

This brief sketch of the geography of Yakutat bay, together with the accompanying outline map of Alaska (plate 2), will, it is hoped, aid in making intelligible the following historical sketch and the narrative of the present expedition.

1. This matter will be discussed in part IV of this paper, where it is also shown that Yakutat bay itself was formerly occupied by glacial ice.