On one occasion the Hassler encountered one of those sudden and startling flaws of wind common to the Strait. The breeze, which had been strong all day, increased with sudden fury just as the vessel was passing through a rather narrow channel, which gave the wind the additional force of compression. In an inconceivably short time, the channel was lashed into a white foam; the roar of wind and water was so great you could not hear yourself speak, though the hoarse shout of command and the answering cry of the sailors rose above the storm. To add to the confusion, a loose sail slatted as if it would tear itself in pieces, with that sharp, angry, rending sound which only a broad spread of loose canvas can make. It became impossible to hold the vessel against the amazing power of the blast, and the Captain turned her round with the intention of putting her into Borja Bay, not far from which, by good fortune, she chanced to be. As she came broadside to the wind in turning, it seemed as if she must be blown over, so violently did she careen. Once safely round, she flew before the wind, which now became her ally instead of her enemy, and by its aid she was soon abreast of Borja Bay. Never was there a more sudden transition from chaos to peace than that which ensued as she turned in from the tumult in the main channel to the quiet waters of the bay. The Hassler almost filled the tiny harbor shut in between mountains. She lay there safe and sheltered in breathless calm, while the storm raged and howled outside. These frequent, almost land-locked coves, are the safety of navigators in these straits; but after this day's experience, it was easy to understand how sailing vessels may be kept waiting for months between two such harbors, struggling vainly to make a few miles and constantly driven back by sudden squalls.
In this exquisite mountain-locked harbor, the vessel was weather-bound for a couple of days. Count Pourtales availed himself of this opportunity to ascend one of the summits. Up to a height of fifteen hundred feet, the rock was characterized by the smoothed, rounded surfaces which Agassiz had observed along his whole route in the Strait. Above that height all was broken and rugged, the line of separation being as defined as on any valley wall in Switzerland. It was again impossible to decide, on such short observation, whether these effects were due to local glacial action, or whether they belonged to an earlier general ice-period. But Agassiz became satisfied, as he advanced, that the two sets of phenomena existed together, as in the northern hemisphere. The general aspect of the opposite walls of the Strait confirmed him in the idea that the sheet of ice in its former extension had advanced from south to north, grinding its way against and over the southern wall to the plains beyond. In short, he was convinced that, as a sheet of ice has covered the northern portion of the globe, so a sheet of ice has covered also the southern portion, advancing, in both instances, far toward the equatorial regions. His observations in Europe, in North America, and in Brazil seemed here to have their closing chapter.
With these facts in his mind, he did not fail to pause before Glacier Bay, noted for its immense glacier, which seems, as seen from the main channel, to plunge sheer down into the waters of the bay. A boat party was soon formed to accompany him to the glacier. It proved less easy of access than it looked at a distance. A broad belt of wood, growing, as Agassiz afterward found, on an accumulation of old terminal moraines, spanned the lower valley from side to side. Through this wood there poured a glacial river, emptying itself into the bay. Strange to say, this glacier-washed forest, touching the ice on one side and the sea on the other, was full of flowers. The red bells of the glossy-leaved Desfontainia, the lovely pink blossoms of the Phylesia, the crimson berries of the Pennetia, stood out in bright relief from a background of mossy tree-trunks and rocks. After an hour's walking, made laborious by the spongy character of the ground,—a mixture of loose soil and decaying vegetation, in which one sank knee-deep,—the gleam of the ice began to shimmer through the trees; and issuing from the wood, the party found themselves in front of a glacier wall, stretching across the whole valley and broken into deep rifts, caves, and crevasses of dark blue ice. The glacier was actually about a mile wide; but as the central portion was pressed forward in advance of the sides, the whole front was not presented at once. It formed a sharp crescent, with the curve turned outward. One of the caves in this front wall was some thirty or forty feet high, about a hundred feet deep, and two or three yards wide at the entrance. At the further end it narrowed to a mere gallery, where the roof was pierced by a circular window, quite symmetrical in shape, through which one looked up to the blue sky and drifting clouds. There must be strange effects in this ice-cavern, when the sun is high and sends a shaft of light through its one window to illuminate the interior.
This first excursion was a mere reconnaissance. An approximate idea of the dimensions of the glacier, and some details of its structure, were obtained on a second visit the following day. The anchorage for the night was in Playa Parda Cove, one of the most beautiful of the many beautiful harbors of the Magellan Strait. It is entered by a deep, narrow slit, cut into the mountains on the northern side of the Strait, and widening at its farther end into a kind of pocket or basin, hemmed in between rocky walls bordered by forests, and overhung by snow and ice-fields. The next morning at half-past three o'clock, just as moonlight was fading before the dawn, and the mountains were touched with the coming day, the reveille was sounded for those who were to return to Glacier Bay. This time Agassiz divided his force so that they could act independently of each other, though under a general plan laid out by him. M. de Pourtales and Dr. Steindachner ascended the mountain to the left of the valley, following its ridge, in the hope of reaching a position from which they could discover the source and the full length of the glacier. In this they did not succeed, though M. de Pourtales estimated its length, as far as he could see from any one point, to be about three miles, beyond which it was lost in the higher range. It made part of a net-work of glaciers running back into a large massif of mountains, and fed by many a neve on their upper slopes. The depth as well as the length of this glacier remains somewhat problematical, and indeed all the estimates in so cursory a survey must be considered as approximations rather than positive results. The glazed surface of the ice is an impediment to any examination from the upper side. It would be impossible to spring from brink to brink of a crevasse, as is so constantly done by explorers of Alpine glaciers where the edges of the cracks are often snowy or granular. Here the edges of the crevasses are sharp and hard, and to spring across one of any size would be almost certain death. There is no hold for an Alpine stock, no grappling point for hands or feet. Any investigation from the upper surface would, therefore, require special apparatus, and much more time than Agassiz and his party could give. Neither was an approach from the side very easy. The glacier arches so much in the centre, and slopes away so steeply, that when one is in the lateral depression between it and the mountain, one faces an almost perpendicular wall of ice, which blocks the vision completely. M. de Pourtales measured one of the crevasses in this wall, and found that it had a depth of some seventy feet. Judging from the remarkable convexity of the glacier, it can hardly be less in the centre than two or three times its thickness on the edges, —something over two hundred feet, therefore. Probably none of these glaciers of the Strait of Magellan are as thick as those of Switzerland, though they are often much broader. The mountains are not so high, the valleys not so deep, as in the Alps; the ice is consequently not packed into such confined troughs. By some of the party an attempt was made to ascertain the rate of movement, signals having been adjusted the day before for its measurement. During the middle of the day, it advanced at the rate of ten inches and a fraction in five hours. One such isolated observation is of course of little comparative value. For himself, Agassiz reserved the study of the bay, the ancient bed of the glacier in its former extension. He spent the day in cruising about the bay in the steam-launch, landing at every point he wished to investigate. His first care was to examine minutely the valley walls over which the glacier must once have moved. Every characteristic feature, known in the Alps as the work of the glaciers, was not only easily recognizable here, but as perfectly preserved as anywhere in Switzerland. The rounded knolls to which De Saussure first gave the name of roches moutonnees were smoothed, polished, scratched, and grooved in the direction of the ice movement, the marks running mostly from south to north, or nearly so. The general trend of the scratches and furrows showed them to have been continuous from one knoll to another. The furrows were of various dimensions, sometimes shallow and several inches broad, sometimes narrow with more defined limits, gradually passing into mere lines on a very smoothly polished surface. Even the curious notches scooped out of the even surfaces, and technically called "coups de gouge," were not wanting. In some places the seams of harder rock stood out for a quarter of an inch or so above adjoining decomposed surfaces; in such instances the dike alone retained the glacial marks, which had been worn away from the softer rock.
The old moraines were numerous and admirably well preserved. Agassiz examined with especial care one colossal lateral moraine, standing about two miles below the present terminus of the ice and five hundred feet above the sea-level. It consisted of the same rocks as those found on the present terminal moraine, part of them being rounded and worn, while large, angular boulders rested above the smaller materials. This moraine forms a dam across a trough in the valley wall, and holds back the waters of a beautiful lake, about a thousand feet in length and five hundred in width, shutting it in just as the Lake of Meril in Switzerland is held in its basin by the glacier of Aletsch. There are erratics some two or three hundred feet above this great moraine, showing that the glacier must have been more than five hundred feet thick when it left this accumulation of loose materials at such a height. It then united, however, with a large glacier more to the west. Its greatest thickness, as an independent glacier, is no doubt marked, not by the boulders lying higher up, but by the large moraine which shuts in the lake. The direct connection of this moraine with the glacier in its former extension is still further shown by two other moraines, on lower levels and less perfect, but having the same relation to the present terminus of the ice. The lower of these is only one hundred and fifty feet above the actual level of the glacier. These three moraines occur on the western slope of the bay. The eastern slope is more broken, and while the rounded knolls are quite as distinct and characteristic, the erratics are more loosely scattered over the surface. In mineralogical character they agree with those on the western wall of the bay. Upon the summits of some small islands at the entrance of the bay, there are also some remnants of terminal moraines, formed by the glacier when it reached the main channel; that is, when it was some three miles longer than now.
The more recent oscillations, marking the advance and retreat of the glacier within certain limits, are shown by the successive moraines heaped up in advance of the present terminal wall. The central motion here, as in all the Swiss glaciers, is greater than the lateral, the ice being pushed forward in the middle faster than on the sides. But there would seem to be more than one axis of progression in this broad mass of ice; for though the centre is pushed out beyond the rest, the terminal wall does not present one uniform curve, but forms a number of more or less projecting angles or folds. A few feet in front of this wall is a ridge of loose materials, stones, pebbles, and boulders, repeating exactly the outline of the ice where it now stands; a few feet in advance of this, again, is another ridge precisely like it; still a few feet beyond, another; and so on, for four or five concentric zigzag crescent-shaped moraines, followed by two others more or less marked, till they fade into the larger morainic mass, upon which stands the belt of wood dividing the present glacier from the bay. Agassiz counted eight distinct moraines between the glacier and the belt of wood, and four concentric moraines in the wood itself. It is plain that the glacier has ploughed into the forest within some not very remote period, for the trees along its margin are loosened and half uprooted, though not yet altogether decayed. In the presence of the glacier one ceases to wonder at the effects produced by so powerful an agent. This sheet of ice, even in its present reduced extent, is about a mile in width, several miles in length, and at least two hundred feet in depth. Moving forward as it does ceaselessly, and armed below with a gigantic file, consisting of stones, pebbles, and gravel, firmly set in the ice, who can wonder that it should grind, furrow, round, and polish the surfaces over which it slowly drags its huge weight. At once destroyer and fertilizer, it uproots and blights hundreds of trees in its progress, yet feeds a forest at its feet with countless streams; it grinds the rocks to powder in its merciless mill, and then sends them down, a fructifying soil, to the wooded shore below.
Agassiz would gladly have stayed longer in the neighborhood of Glacier Bay, and have made it the central point of a more detailed examination of the glacial phenomena in the Strait. But the southern winter was opening, and already gave signs of its approach. At dawn on the 26th of March, therefore, the Hassler left her beautiful anchorage in Playa Parda Cove, six large glaciers being in sight from her deck as she came out. The scenery during the morning had a new scientific interest for Agassiz, because the vessel kept along the northern side of the Strait, while the course hitherto had been nearer the southern shore. He could thus better compare the differences between the two walls of the Strait. The fact that the northern wall is more evenly worn, more rounded than the southern, had a special significance for him, as corresponding with like facts in Switzerland, and showing that the ice-sheet had advanced across the Strait with greater force in its ascending than in its descending path. The north side being the strike side, the ice would have pushed against it with greater force. Such a difference between the two sides of any hollow or depression in the direct path of the ice is well known in Switzerland.
Later in the day, a pause was made in Chorocua Bay, where Captain Mayne's chart makes mention of a glacier descending into the water. There is, indeed, a large glacier on its western side, but so inaccessible, that any examination of it would have required days rather than hours. No one, however, regretted the afternoon spent here, for the bay was singularly beautiful. On either side, deep gorges, bordered by richly-wooded cliffs and overhung by ice and snow-fields, were cut into the mountains. Where these channels might lead, into what dim recesses of ocean and mountain, could only be conjectured. The bay, with all its inlets and fiords, was still as a church. Voices and laughter seemed an intrusion, and a louder shout came back in echoes from far-off hidden retreats. Only the swift steamer-ducks, as they shot across, broke the glassy surface of the water with their arrow-like wake. From this point the Hassler crossed to Sholl Bay, and anchored at the entrance of Smythe's Channel. As sunset faded over the snow mountains opposite her anchorage, their white reflection lay like marble in the water.