The Hassler Glacier in the Straits of Magellan

WE had dipped our dredges in various ocean depths from the West Indies to the southernmost limits of the continent ; we had examined the moraines of ancient glaciers and the craters of extinct volcanoes on Patagonian shores, and hunted guanacos and ostriches on the adjoining plains ; we had roused the penguins and cormorants by hundreds in their breeding-places on the cliffs of Magdalena Island, and seen the sea-lions lying on the beaches below, and so through manifold adventures by flood and field had come at last on a fine day in March to be lying off Glacier Bay in the Straits of Magellan.

Glacier Bay has been reported by all explorers of the straits in the present century, from Fitzroy, King, and Darwin, down to the last English surveying expedition under Captain Mayne. It derives its name from an immense glacier (not, however, exceptionally large in this land of glaciers), which seems, as you see it from the main channel, to plunge sheer down into the waters of the bay. There being no good anchorage for vessels in its immediate proximity, we took a boat to row to the foot of this great ice sheet. In our absence, Captain Johnson proposed to make a reconnoissance in Notch Cove, an adjoining inlet, where he hoped to find harborage for the night.

Our boat party consisted of Mr. Agassiz, M. de Pourtalès, Dr. Steindachner, Mr. Blake, Mr. Kennedy, Mrs. Johnson, and myself. We rowed to the head of the bay, the Professor pointing out, as we passed along, the modelling and furrowing of its rocky walls, showing everywhere the rounded knolls and ridges, called in Switzerland roches moutonnées. They mark the track of the glacier in past times, when it filled the bay and ploughed its way down to the entrance. This was by no means the first time that we had observed them. Passing along the main channel of the straits, enclosed as it is between high rugged walls opening out on either hand into picturesque valleys which abut at their farther end against the loftier ranges of snow mountains, we had seen the same appearances. The sides of these valleys as well as the nearer cliffs in their lower portion, and sometimes, indeed, for their whole height, are moulouné, as the Swiss say of their Alpine surfaces ; that is, the shoulders of the mountains are rounded as are all the inequalities on their lower slopes, forming sometimes long, softly swelling mounds, sometimes bulging knolls or protuberances, while above are the jagged peaks of the higher summits. In the Alps the action of the glaciers is going on in sight of all, and their immediate effects can be compared with the appearances produced by glaciers of past times in the same region. Even the ignorant Swiss peasant knows that his roches moulonnées have been produced by the masses of ice moving over the lower ridges of the mountains, while the upper peaks rising above the ice have not been subjected to any such contact, and therefore remain rough and abrupt. Here in the Straits of Magellan the aspect is the same. Looking up the lateral valleys or from base to summit of the nearer heights enclosing the channel, the softly moulded ridges and hummocks, the swelling shoulders, mounds, and knolls are exactly like those of the Alps, while the jagged peaks above stand out beyond the line of glacial action in the same strongly marked contrast. Indeed, upon comparing some of the plates from Mr. Agassiz’s Etudes sur les Glaciers and Systè time glaciaire, taken in the Alps expressly to display this special feature, we have all agreed that the drawings might with very little change have been made in the Straits of Magellan. Upon reaching the beach at the head of the bay, we found that the glacier did not come down to the water, as it had appeared to do from the ship, but that we were separated from it by a transverse belt of woods spanning the valley from side to side and growing, as we afterwards found, on an accumulation of ancient moraines.¹ A glacial river poured through this wood and emptied into the bay, the water having the milky color so peculiar in the glacial streams of Switzerland. There was no time to lose, and we plunged at once into the forest. Mr. Agassiz, M. de Pourtalès, Dr. Steindachner, and Mr. Blake followed the stream as the shorter path. Mrs. Johnson and myself with Mr. Kennedy took our way (not path, for path there was none) to the left of the river, where Mr. Kennedy thought he might cut a trail through the trees, and save us the fatigue of wading or fording. We had not gone many yards before we almost forgot the glacier to which we were bound, in the beauty of the forest. On first reading Darwin’s delightful narrative of his journey through the Straits of Magellan, I was struck with his frequent use of the words “dusky forests”; the phrase took hold of my imagination as at once vague and yet expressive, as if some dim mystery hung about these pathless woods. Being here, I understand its meaning. Looking upon the forests from without as one sees them clothing the face of the country or rising from the shore upon the rugged hillsides, there is something sombre in their character. They lack the tremulous, lighter, more yellow greens which checker the deeper shades of the woods with us. They are, on the whole, darker in their general aspect; and near the shore, for some reason, perhaps on account of the prevalent winds, are apt to have blighted trees along their outer edge. But once within the forest, this impression disappears in great degree. I have never been more surprised than to find that this belt of wood separating us from the glacier, touching the ice on one side, the sea on the other, and situated in a region esteemed so dreary and wintry, held nevertheless as luxuriant a vegetation in its depths as any forest I had ever seen. In saying this I do not except even the forests of the Amazons, though the trees were neither so lofty nor so various. They did not perhaps exceed in height those of the temperate zone, and were chiefly the evergreen beech and the antarctic beech. But every trunk, every branch, every fallen log, every stone, was cushioned in deep, velvety moss and lichens, and these again overgrown by delicate ferns. Flowers were abundant. The lovely pink blossoms of the Phylesia, the closer and darker red bells of the holly-leaved Desfontainia, the small, white clusters of the Arbutus, and the rich crimson berries of the Peunetia, were brought out in bright relief against a background of mossy tree-trunks and rocks, often disposed with a picturesque effect which seemed intentional. It was not easy to force one’s way through this overgrown wood, soggy with moisture, knee-deep in a soft verdure delicious to the eye but treacherous to the foot. Our indefatigable friend Mr. Kennedy preceded us with an axe, and cleared the way before us with untiring strength and patience. Still a single arm cannot hew an easy path through a primitive forest. The most he could do was to make the impossible possible, or rather the impassable passable. We climbed over and under great fallen trees, fell into holes and clambered out of them, and often took to the bed of the stream, wading through it where we could do no better. Where the river was too deep for us and very Swift, we crossed on a fallen trunk. It would have been a perilous bridge, wet, slippery, and moss-grown as it was, had not Mr. Kennedy cut a smaller tree stem to serve as a hand-rail, he holding an end on one bank of the stream while the ship carpenter steadied it on the opposite side, and we crept cautiously across, one at a time. After about an hour of this walking we began to catch glimpses of the ice gleaming between the trees, and following the margin of the river, which assumed more and more the character of a cascade as we approached its source, we issued from the wood in front of an extensive wall of ice spanning the valley for its whole width, and broken at its terminus into numerous deep rifts, caves, and crevasses of that dark, transparent blue so well known to travellers in the ice caves of the Rosenlaui glacier.

I leave the reader to imagine, for it would be futile to describe, the feeling with which we found ourselves in face of this wonderful spectacle. A large glacier is always an impressive sight, but there was something in the loneliness of this one, so far removed from the haunts of men, rarely, if ever, visited before, that heightened the awe and admiration with which we looked upon it. The whole extent of the terminal wall is not seen at the spot where we came out from the forest. The glacier is about a mile in width, and near the centre the front wall makes an abrupt angle, so that the complete breadth is not presented at any one point of view. We found Mr. Agassiz, who had arrived half an hour before us, busily engaged in examining this end of the terminal wall, while his companions had followed the face of the glacier to its other extremity. We wandered about for a long time, enjoying the beauty of the scene and the fantastic forms assumed by die ice. We walked for a little distance up its surface ; but as the glacier is very convex, the ascent is steep, and every step had to he cut with an axe, for the ice was smooth and shining as glass. The Swiss glaciers are usually broken and soiled at the terminus, and the surface so disintegrated towards the lower end that you can walk upon it as upon loose snow; but this was pure and spotless and hard as crystal to its very farthest extremity. We examined the many grottoes and niches cut into the face of the wall, and blue within as if they had borrowed color from the deepest hues of sea and sky. We went into one of these caves. It was some thirty or forty feet high, about a hundred feet deep, and two or three yards wide at the entrance, while it narrowed at the farther end to a mere gallery a foot or two across. Here there was a circular window, quite symmetrical in form, pierced in the roof, through which you could see the sky and the clouds sweeping across.

While we were thus engaged, Mr. Kennedy remained with Mr. Agassiz, adjusting signals for the measurement of the movement of the glacier. There was not time enough on this occasion to determine the rate with accuracy, but the next day, when the working party returned for a more careful investigation, it was ascertained that the ice advanced during the middle of the day at the rate of two inches and a fraction in five hours. This would, no doubt, be less than its advance on a warm day in midsummer, in January or February for instance, which are the. hot months here, and more than its advance in the late fall or winter. It is probably about double the rate of advance at the lower end of the glaciers. I may as well add here, the dimensions of the glacier and some details as to its structure, obtained on the second visit, when carefully systematized observations were made ; the scientific corps then dividing into parties and pursuing their work independently. M. de Pourtalès and Dr. Steindachner, accompanied by Dr. Pitkin, United States surgeon On board the Hassler, followed the mountain to the left of the glacier, hoping to discover its source, but they could never reach a position from which its whole length could be seen.

It is, in truth, but one of a network of glaciers running back into a 1 large massif at mountains, and fed by many a névé on their upper slopes M. de Pourtalès 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. Many lakes of considerable size lie round it in various directions ; he counted three or four. 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 side would therefore require special apparatus and much more time than we could give. Neither is an approach from the side very easy. The glacier arches so much in the centre, and slopes away so steeply, that when you are in the lateral depression between it and the mountain, you face an almost perpendicular wall of ice, which blocks your vision completely. M. de Pountalès measured one of the crevasses, in this wall, and found that it gave a depth of some seventy feet. 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. Probably, however, none of these glaciers of the Straits of Magellan are so 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 therefore not packed into such confined troughs. Indeed, the glaciers in this region often lie like broad fields of ice on open slopes ol the mountains, or cap their summits in evenly rounded domes descending low upon their flanks. But while the general aspect differs in many respects from the Alpine glaciers, the action of the ice is the same. It has moulded its banks into the same rounded and polished surfaces, and has left its tide-marks in the successive moraines marking the steps of its retreat.

On the second visit Mr. Agassiz reserved for himself the study of the bay, the ancient bed of the glacier in its former extension, accompanied by Captain Johnson, who is always ready to facilitate his researches by every means in his power. He passed the day in cruising about the bay in the steam launch, landing at any point he wished to investigate. His first care was to examine minutely the valley walls over which the glacier must have moved formerly. 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 moutonnées 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 scratches and furrows show by their general trend that they are continuous from one knoll to another. The furrows are of various dimensions, sometimes shallow and several inches broad, sometimes narrow with more defined limits gradually passing to mere lines on a very smoothly polished surface. Even the curious excavations scooped out of the even surfaces technically called coups de gouge are not wanting. Sometimes 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. In short, the whole story is identical here with that of glacial action in the Alps or in the more northern parts of Europe. Even did these ice-worn surfaces not exist, the distribution of loose materials along the sides of the valley and the remains of old moraines would show, independently of all other signs, that the glacier had once extended far beyond its present limits.

The moraines were admirably well preserved and numerous. Mr. 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 rock as those found in the present terminal moraine, part of them being rounded and worn, while large angular boulders rest 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 Merrill in Switzerland is shut into 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 these 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 bearing 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, however, they agree with those at the present terminus of the glacier, and with those on the western wall of the bay. Upon the summits of small islands at the entrance of the bay there are 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.

While Mr. Agassiz was studying the ancient glacier, and M. de Pourtalès was measuring the present one, Dr. Hill and Dr. White were photographing certain points of the internal structure of the ice and of its action upon surrounding surfaces ; and Mr. Perry, one of the officers, with the assistance of the signals, adjusted on the previous day by Mr. Kennedy, ascertained the rate of actual movement.

The general progression of the glacier and its oscillations of advance and retreat within certain limits, are plainly 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 margins. But there would seem to be more than one axis of progression in this broad mass of ice ; for though the centre is in advance of the rest, the terminal wall does not present one crescent-shaped face, but forms a number of more or less protruding 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 is again another ridge precisely like it ; 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 woods we had crossed in order to reach the glacier. There are eight distinct moraines between the glacier and the belt of woods separating it from the beach. The belt of woods again rests, as Mr. Agassiz ascertained by examination, upon four concentric moraines.

On the spot it is easy to understand the process by which these moraines have been formed. Stooping down in any of the open rifts or caves in the ice, you can look between its lower surface and the ground and see the mass of materials, of all sorts and sizes, carried along under the glacier and pushed forward by it. Thus shoved onward they are crowded up into a ridge, which is left when the melting ice retreats after a hot summer, lying on the ground and retaining exactly the outline received from the glacier itself. Wherever the motion has been most rapid, the morainic material has been driven outward ; wherever it has been retarded, the morainic material has been delayed also. It has, in short, advanced just so far, and no farther, than the ice itself. Thus the moraines, until time and the gradual growth of vegetation upon them have remodelled them, represent the outline of the glacier by which they were built. From their appearance Mr. Agassiz thought that the moraines immediately in front of the glacier marked its oscillation within a comparatively short period. They are entirely destitute of vegetation. In advance of them is one both higher and broader than the rest, which must be considerably older, since mosses, lichens, and a few other plants are scattered over it. This moraine leans against trees, which are all blighted and bent toward the valley below, the whole green forest being bordered by a row of dead trees brought out in grim relief against the verdure behind. It is plain that the glacier has ploughed into the forest, loosening and half uprooting the trees along its margin, and this at a period not very remote, for the dead trees are not yet altogether rotten and decayed. A little lower down, separated by a small pool from the barren moraines, the fresh forest covers the whole ground. That this also, so far as it fills the bed of the valley, grows upon morainic accumulation is seen, not only by the mass of loose stones and boulders forming the floor of the forest and bound together by overgrowth of moss and a verdant soil, but also from the cuts made by the river, the banks of which are wholly morainic.

In the presence of the glacier you cease to wonder at the effects produced by so powerful an agent. This sheet of ice in its present extension is, as we have seen, about a mile in width, several miles in length, and at least some 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, fitting itself with anaconda-like flexibility to every inequality of the soil ! At once destroyer and fertilizer, it uproots and blights hundreds of trees in its progress, yet feeds a forest at its foot with countless streams ; it grinds the rocks to powder in its merciless mill, and then sends them down a fructifying soil to the valleys below. After we had wandered about till we were tired, the sailors, most of whom had by this time found their way up from the beach, built a fire on the moraine, near which Mrs. Johnson and I were glad to sit down and dry our feet, while we waited for the gentlemen to finish their work. We were beginning to discover that we were hungry, for the picturesque will not, after all, feed the carnal man or woman. We were making a mutual confession on this point, when we heard a shout from the woods, and saw the Captain, with several of the ship’s company, issuing from the trees, followed by two men carrying a lunch-basket. By this time the other party had returned from the eastern end of the terminal wall, bringing a report that it was even more beautiful there, the ice being cut into very striking peaks and towers and other jagged, picturesque forms, while below were arches and caves pierced by windows. Mr. Agassiz had already gone on in this direction, hut we had no time to follow him, even had our strength been equal to it. The Captain brought news that the Hassler could not safely cross the bar into Notch Cove, where he had hoped to anchor, and that we must return promptly in order to reach Playa Parda Cove, the nearest harbor, before nightfall. All stragglers were therefore recalled, and after a short rest, while we lunched around our fire, now a comfortable crackling blaze, we bade good by to the great, beautiful icesheet, and betook ourselves to the woods once more. Somewhat assisted by the tracks of the various parties who had followed each other through this labyrinth in the course of the day, we reached the beach in less time than we had spent in going to the glacier. The boat was pushed up into the little glacial river, and taking a parting draught from the icy cold water, which freshens the bay for a long distance, we stepped in and were off. Returning on board we dined gayly, not forgetting to christen the glacier in a glass of champagne. At Mr. Agassiz’s suggestion it was called the “ Hassler ” glacier, in memory of the United States Coast Survey and of the vessel in which our trip was made. Two hours later we were quietly anchored in Playa Parda Cove. This beautiful little harbor is formed by a deep narrow slit, cut into the mountains on the northern side of the straits, and widening out at its farther end into a kind of pocket or basin, sunk so deep between rocky walls that it seems like a sheltered lake. At ten o'clock at night I went on deck ; there was not a cloud in the sky, and it was brilliant moonlight. Looking toward the opening of the cove, a snow mountain lay dim and pale like a white dream in the distance ; around us rose dark rugged walls of rock, and the water, still as glass, held it all as in a picture.

Elizabeth C. Agassiz.