Louis Agassiz: His Life and Correspondence Part 32

FROM AGa.s.sIZ TO PROFESSOR PEIRCE.

CAMBRIDGE, February 20, 1871.

. . .I am overjoyed at the prospect your letter opens before me. Of course I will go, unless Brown-Sequard orders me positively to stay on terra firma. But even then, I should like to have a hand in arranging the party, as I feel there never was, and is not likely soon again to be, such an opportunity for promoting the cause of science generally, and that of natural history in particular. I would like Pourtales and Alex to be of the party, and both would gladly join if they can. Both are as much interested about it as I am, and I have no doubt between us we may organize a working team, strong enough to do something creditable. It seems to me that the best plan to pursue in the survey would be to select carefully a few points (as many as time would allow) on sh.o.r.e, from which to work at right angles with the coast, to as great a distance as the results would justify, and then move on to some other head-land. If this plan be adopted, it would be desirable to have one additional observer to make collections on sh.o.r.e, to connect with the result of the dredgings. This would be the more important as, with the exception of Brazil, hardly anything is known of the sh.o.r.e faunae upon the greater part of the South American coast. For sh.o.r.e observations I should like a man of the calibre of Dr.

Steindachner, who has spent a year on the coast of Senegal, and would thus bring a knowledge of the opposite side of the Atlantic as a starting basis of comparison. . .

After consultation with his physicians, it was decided that Aga.s.siz might safely undertake the voyage in the Ha.s.sler, that it might indeed be of benefit to his health. His party of naturalists, as finally made up, consisted of Aga.s.siz himself, Count de Pourtales, Dr. Franz Steindachner, and Mr. Blake, a young student from the Museum, who accompanied Aga.s.siz as a.s.sistant and draughtsman. Dr.

Thomas Hill, ex-president of Harvard University, was also on the expedition, and though engaged in special investigations of his own, he joined in all the work with genial interest. The vessel was commanded by Captain (now Commodore) Philip C. Johnson, whose courtesy and kindness made the Ha.s.sler a floating home to the guests on board. So earnest and active was the sympathy felt by him and his officers in the scientific interests of the expedition, that they might be counted as a valuable additional volunteer corps. Among them should be counted Dr. William White, of Philadelphia, who accompanied the expedition in a partly professional, partly scientific capacity.

The hopes Aga.s.siz had formed of this expedition, as high as those of any young explorer, were only partially fulfilled. His enthusiasm, though it had the ardor of youth, had none of its vagueness. In a letter to Mr. Peirce, published in the Museum Bulletin at this time, there is this pa.s.sage: "If this world of ours is the work of intelligence and not merely the product of force and matter, the human mind, as a part of the whole, should so chime with it, that from what is known it may reach the unknown. If this be so, the knowledge gathered should, within the limits of error which its imperfection renders unavoidable, enable us to foretell what we are likely to find in the deepest abysses of the sea." He looked, in short, for the solution of special problems directly connected with all his previous work. He believed the deeper sea would show forms of life akin to animals of earlier geological times, throwing new light on the relation between the fossil and the living world. In the letter above quoted, he even named the species he expected to find most prevalent in those greater depths: as, for instance, representatives of the older forms of Ganoids and Selachians; Cephalopods, resembling the more ancient chambered sh.e.l.ls; Gasteropods, recalling the tertiary and cretaceous types; and Acephala, resembling those of the jura.s.sic and cretaceous formations. He expected to find Crustaceans also, more nearly approaching the ancient Trilobites than those now living on the surface of the globe; and among Radiates he looked for the older forms of sea-urchins, star-fishes, and corals.

Although the collections brought together on this cruise were rich and interesting, they gave but imperfect answers to these comprehensive questions. Owing to defects in the dredging apparatus, the hauls from the greatest depths were lost.

With reference to the glacial period he antic.i.p.ated still more positive results. In the same letter the following pa.s.sage occurs: "There is, however, still one kind of evidence wanting, to remove all doubt that the greater extension of glaciers in former ages was connected with cosmic changes in the physical condition of our globe. Namely, all the phenomena relating to the glacial period must be found in the southern hemisphere, accompanied by the same characteristic features as in the north, but with this essential difference,--that everything must be reversed. The trend of the glacial abrasions must be from the south northward, the lee-side of abraded rocks must be on the north side of the hills and mountain ranges, and the boulders must have traveled from the south to their present position. Whether this be so or not, has not yet been ascertained by direct observation. I expect to find it so throughout the temperate and cold zones of the southern hemisphere, with the exception of the present glaciers of Terra del Fuego and Patagonia, which may have transported boulders in every direction.

Even in Europe, geologists have not yet sufficiently discriminated between local glaciers and the phenomena connected with their different degrees of successive retreat on the one hand; and, on the other, the facts indicating the action of an extensive sheet of ice moving over the whole continent from north to south. Among the facts already known from the southern hemisphere are the so-called rivers of stone in the Falkland Islands, which attracted the attention of Darwin during his cruise with Captain Fitzroy, and which have remained an enigma to this day. I believe it will not be difficult to explain their origin in the light of the glacial theory, and I fancy they may turn out to be ground moraines similar to the 'horsebacks' in Maine.

"You may ask what this question of drift has to do with deep-sea dredging? The connection is closer than may at first appear. If drift is not of glacial origin, but is the product of marine currents, its formation at once becomes a matter for the Coast Survey to investigate. But I believe it will be found in the end, that so far from being acc.u.mulated by the sea, the drift of the Patagonian lowlands has been worn away by the sea to its present outline, like the northern sh.o.r.es of South America and Brazil.". . .

This is not the place for a detailed account of the voyage of the Ha.s.sler, but enough may be told to show something of Aga.s.siz's own share in it. A journal of scientific and personal experience, kept by Mrs. Aga.s.siz under his direction, was nearly ready for publication at the time of his death. The two next chapters, devoted to the cruise of the Ha.s.sler, are taken from that ma.n.u.script. A portion of it appeared many years ago in the pages of the "Atlantic Monthly."

CHAPTER 23.

1871-1872: AGE 64-65.

Sailing of the Ha.s.sler.

Sarga.s.sum Fields.

Dredging at Barbados.

From the West Indies to Rio de Janeiro.

Monte Video.

Quarantine.

Glacial Traces in the Bay of Monte Video.

The Gulf of Mathias.

Dredging off Gulf of St. George.

Dredging off Cape Virgens.

Possession Bay.

Salt Pool.

Moraine.

Sandy Point.

Cruise through the Straits.

Scenery.

Wind Storm.

Borja Bay.

Glacier Bay.

Visit to the Glacier.

Chorocua Bay.

The vessel was to have started in August, but, owing to various delays in her completion, she was not ready for sea until the late autumn. She finally sailed on December 4, 1871, on a gray afternoon, which ushered in the first snow-storm of the New England winter. Bound for warmer skies, she was, however, soon in the waters of the Gulf Stream, where the work of collecting began in the fields of Sarga.s.sum, those drifting, wide-spread expanses of loose sea-weed carrying a countless population, lilliputian in size, to be sure, but very various in character. Aga.s.siz was no less interested than other naturalists have been in the old question so long asked and still unanswered, about the Sarga.s.sum.

"Where is its home, and what its origin? Does it float, a rootless wanderer on the deep, or has it broken away from some submarine attachment?" He had pa.s.sed through the same region before, in going to Brazil, but then he was on a large ocean steamer, while from the little Ha.s.sler, of 360 tons, one could almost fish by hand from the Sarga.s.sum fields. Some of the chief results are given in the following letter.

TO PROFESSOR PEIRCE.

ST. THOMAS, December 15, 1871.

. . .As soon as we reached the Gulf Stream we began work. Indeed, Pourtales had organized a party to study the temperatures as soon as we pa.s.sed Gay Head, and will himself report to you his results.

My own attention was entirely turned to the Gulf weed and its inhabitants, of which we made extensive collections. Our observations on the floating weed itself favor the view of those who believe it to be torn from rocks, on which Sarga.s.sum naturally grows. I made a simple experiment which seems to me conclusive. Any branch of the sea-weed which is deprived of its FLOATS sinks at once to the bottom of the water, and these floats are not likely to be the first parts developed from the spores. Moreover, after examining large quant.i.ties of the weed, I have not seen a single branch, however small, which did not show marks of having been torn from a solid attachment.

You may hardly feel an interest in my zoological observations, but I am sure you will be glad to learn that we had the best opportunity of carefully examining most of the animals known to inhabit the Gulf weed, and some also which I did not know to occur among them. The most interesting discovery of our voyage thus far, however, is that of a nest built by a fish, and floating on the broad ocean with its living freight. On the 13th, Mr. Mansfield, one of our officers, brought me a ball of Gulf weed which he had just picked up, and which excited my curiosity to the utmost. It was a round ma.s.s of Sarga.s.sum about the size of two fists. The bulk of the ball was made up of closely packed branches and leaves, held together by fine threads, running through them in every direction, while other branches hung more loosely from the margin. Placed in a large bowl of water it became apparent that the loose branches served to keep the central ma.s.s floating, cradle-like, between them. The elastic threads, which held the ball of Gulf weed together, were beaded at intervals, sometimes two or three beads close together, or a bunch of them hanging from the same cl.u.s.ter of threads, or occasionally scattered at a greater distance from each other. Nowhere was there much regularity in the distribution of the beads. They were scattered pretty uniformly throughout the whole ball of seaweed, and were themselves about the size of an ordinary pin's head. Evidently we had before us a nest of the most curious kind, full of eggs. What animal could have built this singular nest? It did not take long to ascertain the cla.s.s to which it belonged. A common pocket lens revealed at once two large eyes on the side of the head, and a tail bent over the back of the body, as in the embryo of ordinary fishes shortly before the period of hatching. The many empty egg cases in the nest gave promise of an early opportunity of seeing some embryos, freeing themselves from their envelope. Meanwhile a number of these eggs containing live embryos were cut out of the nest and placed in separate gla.s.s jars, in order to multiply the chances of preserving them; while the nest as a whole was secured in alcohol, as a memorial of our discovery.

The next day I found two embryos in my gla.s.s jars; they moved occasionally in jerks, and then rested a long time motionless on the bottom of the jar. On the third day I had over a dozen of these young fishes, the oldest beginning to be more active. I need not relate in detail the evidence I soon obtained that these embryos were actually fishes. . .But what kind of fish was it? At about the time of hatching, the fins differ too much from those of the adult, and the general form has too few peculiarities, to give any clew to this problem. I could only suppose it would prove to be one of the pelagic species of the Atlantic. In former years I had made a careful study of the pigment cells of the skin in a variety of young fishes, and I now resorted to this method to identify my embryos. Happily we had on board several pelagic fishes alive. The very first comparison I made gave the desired result. The pigment cell of a young Chironectes pictus proved identical with those of our little embryos. It thus stands, as a well authenticated fact, that the common pelagic Chironectes of the Atlantic, named Ch.

pictus by Cuvier, builds a nest for its eggs in which the progeny is wrapped up with the materials of which the nest itself is composed; and as these materials consist of the living Gulf weed, the fish cradle, rocking upon the deep ocean, is carried along as in an arbor, which affords protection and afterwards food also, to its living freight. This marvelous story acquires additional interest, when we consider the characteristic peculiarities of the genus Chironectes. As its name indicates, it has fin-like hands; that is to say, the pectoral fins are supported by a kind of long wrist-like appendage, and the rays of the ventrals are not unlike rude fingers. With these limbs these fishes have long been known to attach themselves to sea-weeds, and rather to walk than to swim in their natural element. But now that we know their mode of reproduction, it may fairly be asked if the most important use of their peculiarly constructed fins is not the building of their nest?. . .There thus remains one closing chapter to the story. May some naturalist, becalmed among the Gulf weed, have the good fortune to witness the process by which the nest is built. . .

This whole investigation was of the greatest interest to Aga.s.siz, and, coming so early in the voyage, seemed a pleasant promise of its farther opportunities. The whole s.h.i.+p's company soon shared his enthusiasm, and the very sailors gathered about him in the intervals of their work, or hung on the outskirts of the scientific circle. A pause of a few days was made at one or two of the West Indian islands, at St. Thomas and Barbados. At the latter, the first cast of the large dredge was made on a ledge of shoals in a depth of eighty fathoms, and, among countless other things, a number of stemmed crinoids and comatulae were brought up. An ardent student of the early fossil echinoderms, it was a great pleasure to Aga.s.siz to gather their fresh and living representatives. It was like turning a leaf of the past and finding the subtle thread which connects it with the present.

TO PROFESSOR PEIRCE.

PERNAMBUCO, January 16, 1872.

MY DEAR PEIRCE,

I should have written to you from Barbados, but the day before we left the island was favorable for dredging, and our success in that line was so unexpectedly great, that I could not get away from the specimens, and made the most of them for study while I had the chance. We made only four hauls, in between seventy-five and one hundred and twenty fathoms. But what hauls! Enough to occupy half a dozen competent zoologists for a whole year, if the specimens could be kept fresh for that length of time. The first haul brought up a Chemidium-like sponge; the next gave us a crinoid, very much like the Rhizocrinus lofotensis, but probably different; the third, a living Pleurotomaria; the fourth, a new genus of Spatangoids, etc., etc., not to speak of the small fry. We had the crinoid alive for ten or twelve hours. When contracted, the pinnules are pressed against the arms, and the arms themselves shut against one another, so that the whole looks like a swash made up of a few long, coa.r.s.e twines. When the animal opens, the arms at first separate without bending outside, so that the whole looks like an inverted pentapod; but gradually the tips of the arms bend outward as the arms diverge more and more, and when fully expanded the crown has the appearance of a lily of the L. martagon type, in which each petal is curved upon itself, the pinnules of the arms spreading laterally more and more, as the crown is more fully open. I have not been able to detect any motion in the stem traceable to contraction, though there is no stiffness in its bearing. When disturbed, the pinnules of the arms first contract, the arms straighten themselves out, and the whole gradually and slowly closes up. It was a very impressive sight for me to watch the movements of the creature, for it not only told of its own ways, but at the same time afforded a glimpse into the countless ages of the past, when these crinoids, so rare and so rarely seen nowadays, formed a prominent feature of the animal kingdom. I could see, without great effort of the imagination, the shoal of Lockport teeming with the many genera of crinoids which the geologists of New York have rescued from that prolific Silurian deposit, or recall the formations of my native country, in the hill-sides of which also, among fossils indicating shoal water deposits, other crinoids abound, resembling still more closely those we find in these waters. The close affinities of Rhizocrinus with Apiocrinoids are further exemplified by the fact that when the animal dies, it casts off its arms, like Apiocrinus, the head of which is generally found without arms. And now the question may be asked, what is the meaning of the occurrence of these animals in deep waters at the present day, when, in former ages, similar types inhabited shallow seas? Of the fact there can be no doubt, for it is not difficult to adduce satisfactory evidence of the shoal-like character of the Silurian deposits of the State of New York; their horizontal position, combined with the gradual recession of the higher beds in a southerly direction, leaves no doubt upon this point; and in the case of the jura.s.sic formation alluded to above, the combination of the crinoids with fossils common upon coral reefs, and their presence in atolls of that period, are satisfactory proofs of my a.s.sertion. What does it mean, then, when we find the Pentacrinus and Rhizocrinus of the West Indies in deep water only? It seems to me that there is but one explanation of the fact, namely, that in the progress of the earth's growth, we must look for such a displacement of the conditions favorable to the maintenance of certain lower types, as may recall most fully the adaptations of former ages. It was in this sense I alluded, in my first letter to you, to the probability of our finding in deeper water representatives of earlier geological types; and if my explanation is correct, my antic.i.p.ation is also fully sustained. But do the deeper waters of the present const.i.tution of our globe really approximate the conditions for the development of animal life, which existed in the shallower seas of past geological ages? I think they do, or at least I believe they approach it as nearly as anything can in the present order of things upon earth; for the depths of the ocean alone can place animals under a pressure corresponding to that caused by the heavy atmosphere of earlier periods. But, of course, such high pressure as animals meet in great depths cannot be a favorable condition for the development of life; hence the predominance of lower forms in the deep sea. The rapid diminution of light with the increasing depth, and the small amount of free oxygen in these waters under greater and greater pressure, not to speak of other limitations arising from the greater uniformity of the conditions of existence, the reduced amount and less variety of nutritive substances, etc., etc., are so many causes acting in the same direction and with similar results. For all these reasons, I have always expected to find that the animals living in great depths would prove to be of a standing, in the scale of structural complications, inferior to those found in shoal waters or near sh.o.r.e; and the correlation elsewhere pointed out between the standing of animals and their order of succession in geological times (see "Essay on Cla.s.sification ") justifies another form of expression of these facts, namely, that in deeper waters we should expect to find representatives of earlier geological periods. There is in all this nothing which warrants the conclusion that any of the animals now living are lineal descendants of those of earlier ages; nor does their similarity to those of earlier periods justify the statement that the cretaceous formation is still extant. It would be just as true to nature to say that the tertiaries are continued in the tropics, on account of the similarity of the miocene mammalia to those of the torrid zone.

We have another case in the Pleurotomaria. It is not long since it has been made known that the genus Pleurotomaria is not altogether extinct, a single specimen having been discovered about ten years ago in the West Indies. Even Pictet, in the second edition of his Paleontology, still considers Pleurotomaria as extinct, and as belonging to the fossiliferous formations which extend from the Silurian period to the Tertiary. Of the living species found at Marie Galante, nothing is known except the specific characteristics of the sh.e.l.l. We dredged it in one hundred and twenty fathoms, on the west side of Barbados, alive, and kept it alive for twenty-four hours, during which time the animal expanded and showed its remarkable peculiarities. It is unquestionably the type of a distinct family, entirely different from the other Mollusks with which it has been hitherto a.s.sociated. Mr. Blake has made fine colored drawings of it, which may be published at some future time. . .The family of the Pleurotomariae numbers between four and five hundred fossil species, beginning in the Silurian deposits, but especially numerous in the carboniferous and jura.s.sic formations.

The sponges afford another interesting case. When the first number of the great work of Goldfuss, on the fossils of Germany, made its appearance, about half a century ago, the most novel types it made known were several genera of sponges from the jura.s.sic and cretaceous beds, described under the names of Siphonia, Chemidium, and Scyphia. Nothing of the kind has been known among the living to this day; and yet, the first haul of the dredge near Barbados gave us a Chemidium, or, at least, a sponge so much like the fossil Chemidium, that it must remain for future comparisons to determine whether there are any generic differences between our living sponge and the fossil. The next day brought us a genuine Siphonia, another genus thus far only known from the jura.s.sic beds; and it is worth recording, that I noticed in the collection of Governor Rawson another sponge,--brought to him by a fisherman who had caught it on his line, on the coast of Barbados,--which belongs to the genus Scyphia. Thus the three characteristic genera of sponges from the secondary formation, till now supposed to be extinct, are all three represented in the deep waters of the West Indies. . .

Another family of organized beings offers a similar testimony to that already alluded to. If there is a type of Echinoderms characteristic of a geological period, it is the genus Micraster of the cretaceous formation, in its original circ.u.mscription. No species of this genus is known to have existed during the Tertiary era, and no living species has as yet been made known. You may therefore imagine my surprise when the dredge first yielded three specimens of a small species of that particular group of the genus, which is most extensively represented in the upper cretaceous beds.

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 antic.i.p.ated 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, Aga.s.siz 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 Aga.s.siz 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 ma.s.s of tertiary fossils, chiefly immense oysters, mingled, however, with sea-urchins. Superb specimens were secured,--large boulders crowded with colossal sh.e.l.ls 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 anch.o.r.ed 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 pa.s.sed there were among the pleasantest of the voyage to Aga.s.siz. 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 s.h.i.+p after dark, the various parties a.s.sembled 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 Ha.s.sler left her anchorage on this desolate sh.o.r.e on an evening of singular beauty. It was difficult to tell when she was on her way, so quietly did she move through the gla.s.sy 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 phosph.o.r.escence 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 Ha.s.sler 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 sh.o.r.e parties, one of which, under Aga.s.siz's direction, the reader may follow. The land above the first sh.o.r.e 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 Aga.s.siz counted eight. On these terraces, all of which are built, like the sh.o.r.e-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 sh.e.l.ls, identical with those now found along the sh.o.r.e. 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 sh.o.r.e. The second was a genuine moraine, corresponding in every respect to those which occur all over the northern hemisphere. Aga.s.siz 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 ma.s.s had been pushed steeply up on the southern side, and retained so sharp an inclination on that face that but little vegetation had acc.u.mulated 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. Aga.s.siz 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 a.s.ses' Ears. They brought back a variety of game, but their most interesting scientific acquisitions were boulders from the moraine scored with glacial characters, and sh.e.l.ls from the salt pool.

Still accompanied by beautiful weather, the Ha.s.sler anch.o.r.ed at the Elizabeth Islands and at San Magdalena. Here Aga.s.siz 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 anch.o.r.ed, on the 16th March, before Sandy Point, the only permanent settlement in the Strait.

Here there was a pause of several days, which gave Aga.s.siz 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 Aga.s.siz found that portions of them were completely built of fossil sh.e.l.ls. There is an oyster-bank, some one hundred feet high, overhanging the road in ma.s.sive ledges that consist wholly of oyster-valves, with only earth enough to bind them together. He was inclined, from the character of the sh.e.l.ls, to believe that the coal must be cretaceous rather than tertiary.

On Tuesday, the 19th March, the Ha.s.sler 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 Aga.s.siz 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 Ha.s.sler 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 creva.s.se, as well as the many cascades flowing down to join the waters beneath, could be counted as she steamed by them.

Every night she anch.o.r.ed 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 ma.s.ses.

These were weeks of exquisite delight to Aga.s.siz. The vessel often skirted the sh.o.r.e 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 acc.u.mulated 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 ma.s.s 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.