Louis Agassiz: His Life and Correspondence

by Louis Agassiz

Other examples of less importance might be enumerated; suffice it now to add that my expectation of finding in deep waters animals already known, but thus far exceedingly rare in museums, is already in a measure realised. . .

Little can be said of the voyage from the West Indies to Rio de Janeiro. It had the usual vicissitudes of weather, with here and there a flight (so it might justly be called) of flying-fish, a school of porpoises or dog-fish, or a sail in the distance, to break the monotony. At Rio de Janeiro it became evident that the plan of the voyage must be somewhat curtailed. This was made necessary partly by the delays in starting,—in consequence of which the season would be less favorable than had been anticipated along certain portions of the proposed route,—and partly by the defective machinery, which had already given some trouble to the Captain. The Falkland Islands, the Rio Negro, and the Santa Cruz rivers were therefore renounced; with what regret will be understood by those who know how hard it is to be forced to break up a scheme of work, which was originally connected in all its parts. The next pause was at Monte Video; but as there was a strict quarantine, Agassiz was only allowed to land at the Mount, a hill on the western side of the bay, the geology of which he was anxious to examine. He found true erratics—loose pebbles, granite, gneiss, and granitic sandstone, having no resemblance to any native rock in the vicinity—scattered over the whole surface of the hill to its very summit. The hill itself had also the character of the "roches moutonnees" modeled by ice in the northern hemisphere. As these were the most northern erratics and glaciated surfaces reported in the southern hemisphere, the facts there were very interesting to him.

With dredgings off the Rio de la Plata, and along the coast between that and the Rio Negro, the vessel held on her way to the Gulf of Mathias, a deep, broad bay running some hundred miles inland, and situated a little south of the Rio Negro. Here some necessary repairs enforced a pause, of which Agassiz took advantage for dredging and for studying the geology of the cliffs along the north side of the bay. As seen from the vessel, they seemed to be stratified with extraordinary evenness and regularity to within a few feet of the top, the summit being crowned with loose sand. Farther on, they sank to sand dunes piled into rounded banks and softly moulded ledges, like snow-drifts. Landing the next day at a bold bluff marked Cliff End on the charts, he found the lower stratum to consist of a solid mass of tertiary fossils, chiefly immense oysters, mingled, however, with sea-urchins. Superb specimens were secured,—large boulders crowded with colossal shells and perfectly preserved echini. From the top of the cliff, looking inland, only a level plain was seen, stretching as far as the eye could reach, broken by no undulations, and covered with low, scrubby growth. The seine was drawn on the beach, and yielded a good harvest for the fish collection. At evening the vessel anchored at the head of the bay, off the Port of San Antonio. The name would seem to imply some settlement; but a more lonely spot cannot be imagined. More than thirty years ago, Fitzroy had sailed up this bay, partially surveyed it, and marked this harbor on his chart. If any vessel has broken the loneliness of its waters since, no record of any such event has been kept. Of the presence of man, there was no sign. Yet the few days passed there were among the pleasantest of the voyage to Agassiz. The work of the dredge and seine was extremely successful, and the rambles inland were geological excursions of great interest. Here he had the first sight of the guanaco of the Patagonian plains. The weather was fine, and at night-fall, to the golden light of sunset succeeded the fitful glow, over land and water, of the bonfires built by the sailors on the beach. Returning to the ship after dark, the various parties assembled in the wardroom, to talk over the events of the day and lay out plans for the morrow. These are the brightest hours in such a voyage, when the novelty of the locality gives a zest to every walk or row, and all are full of interest in a new and exciting life. One is more tolerant even of monotonous natural features in a country so isolated, so withdrawn from human life and occupation. The very barrenness seems in harmony with the intense solitude.

The Hassler left her anchorage on this desolate shore on an evening of singular beauty. It was difficult to tell when she was on her way, so quietly did she move through the glassy waters, over which the sun went down in burnished gold, leaving the sky without a cloud. The light of the beach fires followed her till they too faded, and only the phosphorescence of the sea attended her into the night. Rough and stormy weather followed this fair start, and only two more dredgings were possible before reaching the Strait of Magellan. One was off the Gulf of St. George, where gigantic star-fishes seemed to have their home. One of them, a superb basket-fish, was not less than a foot and a half in diameter; and another, like a huge sunflower of reddish purple tint, with straight arms, thirty-seven in number, radiating from the disk, was of about the same size. Many beautiful little sea-urchins came up in the same dredging. About fifty miles north of Cape Virgens, in tolerably calm weather, another haul was tried, and this time the dredge returned literally solid with Ophiurans.

On Wednesday, March 13th, on a beautifully clear morning, like the best October weather in New England, the Hassler rounded Cape Virgens and entered the Strait of Magellan. The tide was just on the flood, and all the conditions favorable for her run to her first anchorage in the Strait at Possession Bay. Here the working force divided, to form two shore parties, one of which, under Agassiz's direction, the reader may follow. The land above the first shore bluff at Possession Bay rises to a height of some four hundred feet above the sea-level, in a succession of regular horizontal terraces, of which Agassiz counted eight. On these terraces, all of which are built, like the shore-bluffs, of tertiary deposits, were two curious remnants of a past state of things. The first was a salt-pool lying in a depression on the second terrace, some one hundred and fifty feet above the sea. This pool contained living marine shells, identical with those now found along the shore. Among them were Fusus, Mytilus, Buccinum, Fissurella, Patella, and Voluta, all found in the same numeric relations as those in which they now exist upon the beach below. This pool is altogether too high to be reached by any tidal influence, and undoubtedly indicates an old sea-level, and a comparatively recent upheaval of the shore. The second was a genuine moraine, corresponding in every respect to those which occur all over the northern hemisphere. Agassiz came upon it in ascending to the third terrace above the salt-pool and a little farther inland. It had all the character of a terminal moraine in contact with an actual glacier. It was composed of heterogeneous materials,—large and small pebbles and boulders impacted together in a paste of clayey gravel and sand. The ice had evidently advanced from the south, for the mass had been pushed steeply up on the southern side, and retained so sharp an inclination on that face that but little vegetation had accumulated upon it. The northern side, on the contrary, was covered with soil and overgrown; it sloped gently off,—pebbles and larger stones being scattered beyond it. The pebbles and boulders of this moraine were polished, scratched, and grooved, and bore, in short, all the usual marks of glacial action. Agassiz was naturally delighted with this discovery. It was a new link in the chain of evidence, showing that the drift phenomena are connected at the south as well as at the north with the action of ice, and that the frozen Arctic and Antarctic fields are but remnants of a sheet of ice, which has retreated from the temperate zones of both hemispheres to the polar regions. The party pushed on beyond the moraine to a hill of considerable height, which gave a fine view of the country toward Mount Aymon and the so-called Asses' Ears. They brought back a variety of game, but their most interesting scientific acquisitions were boulders from the moraine scored with glacial characters, and shells from the salt pool.

Still accompanied by beautiful weather, the Hassler anchored at the Elizabeth Islands and at San Magdalena. Here Agassiz had an opportunity of examining the haunts and rookeries of the penguins and cormorants, and obtaining fine specimens of both. As the breeding places and the modes of life of these animals have been described by other travelers, there is nothing new to add from his impressions, until the vessel anchored, on the 16th March, before Sandy Point, the only permanent settlement in the Strait.

Here there was a pause of several days, which gave Agassiz an opportunity to draw the seine with large results for his marine collections. By the courtesy of the Governor, he had also an opportunity of making an excursion along the road leading to the coal-mines. The wooded cliffs, as one ascends the hills toward the mines, are often bold and picturesque, and Agassiz found that portions of them were completely built of fossil shells. There is an oyster-bank, some one hundred feet high, overhanging the road in massive ledges that consist wholly of oyster-valves, with only earth enough to bind them together. He was inclined, from the character of the shells, to believe that the coal must be cretaceous rather than tertiary.

On Tuesday, the 19th March, the Hassler left Sandy Point. The weather was beautiful,—a mellow autumn day with a reminiscence of summer in its genial warmth. The cleft summit of Sarmiento was clear against the sky, and the snow-fields, swept over by alternate light and shadow, seemed full of soft undulations. The evening anchorage was in the Bay of Port Famine, a name which marks the site of Sarmiento's ill-fated colony, and recalls the story of the men who watched and waited there for the help that never came. The stay here was short, and Agassiz spent the time almost wholly in studying the singularly regular, but completely upturned strata which line the beach, with edges so worn down as to be almost completely even with each other.

For many days after this, the Hassler pursued her course, past a seemingly endless panorama of mountains and forests rising into the pale regions of snow and ice, where lay glaciers in which every rift and crevasse, as well as the many cascades flowing down to join the waters beneath, could be counted as she steamed by them. Every night she anchored in the sheltered harbors formed by the inlets and fords which break the base of the rocky walls, and often lead into narrower ocean defiles penetrating, one knows not whither, into the deeper heart of these great mountain masses.

These were weeks of exquisite delight to Agassiz. The vessel often skirted the shore so closely that its geology could be studied from the deck. The rounded shoulders of the mountains, in marked contrast to their peaked and jagged crests, the general character of the snow-fields and glaciers, not crowded into narrow valleys as in Switzerland, but spread out on the open slopes of the loftier ranges, or, dome like, capping their summits,—all this afforded data for comparison with his past experience, and with the knowledge he had accumulated upon like phenomena in other regions. Here, as in the Alps, the abrupt line, where the rounded and worn surfaces of the mountains (moutonnees, as the Swiss say) yield to their sharply cut, jagged crests, showed him the ancient and highest line reached by the glacial action. The long, serrated edge of Mount Tarn, for instance, is like a gigantic saw, while the lower shoulders of the mass are hummocked into a succession of rounded hills. In like manner the two beautiful valleys, separated by a bold bluff called Bachelor's Peak, are symmetrically rounded on their slopes, while their summits are jagged and rough.