This is the second part in a two-part series. Read part one here.
On returning to Bangor, I proceeded at once, according to my original intention, to Mount Desert; but before giving an account of the glacial phenomena on that island, I must say a few words of the physical features of the country between Bangor and the sea. This region is intersected by three distinct ranges of hills, without counting the low range between Brewer and Holden. The first divides the valley of the Penobscot from that of Union River, passing through the townships of Clifton, Holden, and Dedham; the second separates the valley of the Union River from the Coast Range; the third is the Coast Range itself, of which Mount Desert and the elevated islands on either side of it form a part; for all these islands, so broken and picturesque in their outlines, must be looked upon as the higher summits of a partly submerged mountainous ridge. These chains do not run exactly parallel with the coast, their trend being more to the north than that of the shore itself; so that the ridges extending from east to west, across the country, are not exactly at right angles with the normal direction of the glacier marks, though nearly so. It is this formation of the surface of the land which makes the glacial phenomena so interesting between Bangor and the sea, especially where one can connect them with like traces farther north. The road from Bangor to Mount Desert passes in succession over all these ridges, ascending to the heights and descending into the intervening depressions; thus rising three times from the bottom of a valley over the ridge intervening between it and the next valley, before reaching the southern coast of the large shore islands. Over all the elevations and in all the valley bottoms one may trace, in unbroken continuity, and almost at right angles with the direction of the mountains and of the valleys, the same set of lines or glacial marks that we have already traced to the north of Bangor, running due north and south until they disappear under the arm of the sea which separates Mount Desert from the coast. They reappear on the north shore of the island itself, passing over its higher summits to lose themselves finally under the level of the ocean. Not only are the characteristic marks to he followed along the entire length of the road, but the whole surface of the country is moutonnée; namely, worn into those rounded, knoll-like surfaces so frequently alluded to in this and previous articles, and so well known in Switzerland as due to glacial action. Bald Mountain is a striking example of this kind of hill.
This region is literally strewn with huge boulders, sometimes forty or fifty feet high. For the most part they seem to belong to the neighboring hills, and have not travelled a great distance. There are many of these boulders, however, which add their testimony to show that the path of the great ice-plough has been from north to south. This is especially the case with the granite rock of Dedham, so well characterized by its large feldspar crystals, detached masses of which are frequently found to the south of that locality, but never to the north of it. Occasional boulders of a much more northern origin are not wanting. Another link in the evidence is that, wherever the marks are preserved on any abruptly rising ground, they occur on its northern side, and do not appear on the southern one. Evidently the abrading agent advanced from the north, pushed up and over the face presented to it, while the southern face was comparatively protected, the rigid mass no doubt often bridging the opposite declivity without even touching it. I suppose these facts, which perhaps seem insignificant in themselves, must be far less expressive to the general observer than to one who has seen this whole set of phenomena in active operation. To me they have been for many years so familiar in the Alpine valleys, and their aspect in those regions is so identical with the facts above described, that, paradoxical as the statement may seem, the presence of the ice is now an unimportant element to me in the study of glacial phenomena. It is no more essential to the investigator, who has once seen its connection with the facts, than is the flesh which once clothed it to the anatomist who studies the skeleton of a fossil animal. In the face of these facts it seems preposterous to assume that the loose materials and boulders scattered over this interval should have been stranded by icebergs driven inward from the sea-shore by currents or tidal waves. The whole movement, whatever its cause, was unquestionably in the opposite direction. The testimony of the loose materials and erratic boulders is the same all over the United States. They are always of northern birth. I have never seen a single fragment of rock from any more southern locality resting upon glaciated surfaces to the north of them, though I have searched for them from the Atlantic coast to Iowa.
The picturesque island of Mount Desert lies on the southern shore of Maine, in Hancock County, and is separated from the mainland by a narrow arm of the sea. Much higher in the centre than on the margin, its mountains seem, as one draws near, to rise abruptly from the sea. It is cleft through the middle by a deep fiord, known as Somes’s Sound, dividing the southern half of the island into two unequal portions; and its shores are indented by countless bays and coves, which add greatly to its beauty. We entered the island on the northwestern side, from Trenton, and proceeded at once to Bar Harbor, on the eastern side, a favorite resort in summer on account of its broken, varied shore, and of the neighborhood of Green Mountain, with its exquisite lake, sunk in a cup-like depression half-way up the mountain-side, and its magnificent view from the summit. At the very entrance to the island, on passing over the toll-bridge of Trenton, there is an excellent locality for glacial tracks. The striæ are admirably well preserved on some ledges at the Mount Desert end of the bridge. The trend of these marks is north-northeast, instead of due north as in most localities; and here is one of the instances where this slight deflection of the lines is evidently due to the lay of the land. The island is not only highest towards the centre, but narrows at its northern end as it sinks toward the shore, from which it is separated on either side by two deep fords running up into the coast of Maine, and known as Frenchman’s Bay on the east, and Union Bay on the west. It is evident that the mass of ice passing from the mainland over this arm of the sea sunk eastward and westward into these two gorges, acquiring, no doubt, additional thickness thereby, and, in consequence of this change in its normal course, was slightly deflected from its usual direction in working its way up against the shore of Mount Desert. This is shown by the fact that the glacial marks on the northwest shore bear, as I have already said, slightly to the east, while those on the northeast shore bear slightly to the west. On approaching the centre of the island the marks converge towards each other, and regain their primitive direction due north and south, on its more elevated positions. I have often observed in Switzerland like instances, when from some local cause the direction of the movement was slightly deflected to the right and left, converging again at some little distance. In the valley of Hash, between the Hospice of the Grimsel and Guttanen, are several knolls which afford examples in point. On the upper side of these knolls, facing the higher part of the valley, from which large glaciers formerly came down, marks are carried directly up the slope on to the back of the knoll, while on either side they fall away slightly to the right and left, converging again to meet and continue their straight course over the lower slope; showing that, though such knolls, entirely buried beneath the mass of the ice, are no obstacle to its advance, the inequalities of the bottom do affect in a slight degree the direction of the movement, and render the striæ less even than over a level surface. Of course, where the ice is very thick, bottom inequalities will make little impression upon the onward movement of the whole mass; but in proportion as the ice grows less, it adapts itself to the depressions and knolls of the surface, in consequence of which the glacial marks lose the uniformity of their trend.
The morning following my arrival at Bar Harbor I spent in examining the glacial phenomena in its immediate neighborhood. At Bar Harbor itself, the marks bear north and north-northwest. A mile farther south they are all in a north-northwesterly direction. The cove of the Spouting-Horn, however, — a deep recess in the rock, where the surf acts with wonderful force, — is engraved on both sides with lines running due north. On the same side of the island, considerably to the south of Bar Harbor, there is a striking sea-wall composed of coarse materials, thrown up in a line along the shore, formed, no doubt, by some unusually severe storm, coinciding with high-water. It resembles the well-known sea-wall of Chelsea Beach. Behind this wall stretches an extensive marsh, formerly a part of the sea. Somewhat beyond it, on the shore, are two very distinct polished and grooved surfaces, with the lines running due north. On the afternoon of the same day, I ascended Green Mountain. Along the lower part of the road the marks run northwest, then north-northwest, converging more and more toward their normal course, until, after passing the first summit, and thence upward, they lose entirely the slanting direction impressed upon them by the deflection of the ice about Frenchman’s Bay, and run due north again. All the way up the last slope of the mountain, wherever the rock is exposed, may be seen well-engraved fiat surfaces of rose-colored protogine, on which the scratches and grooves sometimes run for twenty feet without any perceptible interruption. On the very summit is a quartz dike cut to the same level with the general outline of the knoll, on which the marks are very distinct. I arrived on the extreme point—where the southern descent is so abrupt that the mountain seems to plunge into the ocean—just at sunset. The sea as far as the eye could reach was still glowing with color; amethyst clouds floated over the numerous islands to the southwest; while on the other side in the gathering shadows lay the little lake midway on the mountain slope, and, below, the many inlets, coves, and islands of Frenchman’s Bay.
On the following day, we crossed to the opposite side of the island, skirting Somes’s Sound, and the next morning entered the sound in a small schooner. A stiff breeze from the north, which obliged us to tack constantly, and made our progress very slow, prevented us from exploring this singular inlet for its whole length; but short as it was, our sail gave me ample opportunity for observing the glacial phenomena along its shores. At the mouth of the sound, before entering the narrows, there are several concentric terminal moraines on both sides of the fiord. No doubt they once stretched across it, and were broken through by the sea. On either side, to the right and left, in ascending the sound, are little valleys running down to the water; and evidently they have all had their local glaciers, for there are terminal moraines at the mouth of each one. These facts only confirmed my anticipations. I had seen, on passing the head of the fiord, in our drive of the previous day, that it must from its formation afford an admirable locality for glacial remains, unless they had been swept away by the sea. The small town of Somesville is beautifully situated at the head of the sound. Approaching it from the east, I observed that the glacial marks which had been pointing due north began to point west-northwest, while on the western side of the settlement they pointed east-northeast. Evidently there is an action here similar to that by which the marks are deflected on the northern shore of the island about Frenchman’s Bay and Union Bay. The mass of ice coming from the north had been gradually sinking into the fiord from opposite sides. Near Somesville church the marks run again due north.
The extensive surfaces of polished and scratched rocks in this locality recall the celebrated Helle-Platten of the valley of Hasli. From Southwest Harbor we followed the shore to Bass Harbor and Seal Cove. There are frequent indications of glacial action along this road, and one or two points of special interest. At Bass Harbor there is a large dike of green trap running at right angles with the tide current. Though regularly overflowed at high-water, the action of the sea has not affected the glacial characters, which are peculiarly distinct at this spot. Not only is the surface of the dike itself deeply scored with striæ and furrows running due north, but, being of a softer quality than the granitic rock which it intersects, it has been cut to a little lower level, and the vertical walls of the fissure are polished, scratched, and grooved in the same way. I met here with one of those incidents showing the character of the working-class in America which always strike a European with astonishment. There was a blacksmith’s shop near this dike, and being extremely anxious to obtain a specimen from it on account of the clearness of its glacial characters, I requested the head workman, who had been watching my observations with a good deal of interest, to break me off a piece. It was not an easy task, for there were no angles, the dike being sunk below the surrounding surface and perfectly smooth. After a time, and not without some hard work, a wedge was driven in, and with the help of a crow-bar two or three very satisfactory specimens were pried out. I naturally wished to pay the man for his labor; but he refused to take anything, saying that he saw I was a geologist travelling for the sake of investigation. He added, that he subscribed for one or two papers and magazines perhaps he should meet with some of the published results of my journey one of these days, and that would be the best reward for the little help he had given. Seeing his interest in the object of my researches, I explained to him the significance of this dike, showed him the direction of the marks pointing straight to the north, and evidently entirely independent of tidal action, since they ran at right angles with it. As I bade him good by, he said, “Henceforth this dike shall be my compass; I shall know when the wind blows due north.” The locality was, indeed, especially interesting from several points of view. It is one of the few instances I have seen in which a dike, being composed of a softer paste than the adjoining rock, has yielded more readily to the ice-plough, and is cut to a lower level, thus forming a broad, flat furrow, the upright walls of which are scored as deeply as the horizontal surface of the dike. Another most important fact is, that the tide daily flows across these marks. Evidently, then, they have not been made by water, since water has no power to erase them, or to obscure them by other lines of the same kind. A mile and a half to the south of Bass. Harbor there is a ledge facing north, on which the glacial characters also point to the north. At Seal Cove, however, on the southwestern shore, the marks have again a north-northwesterly direction. South of Seal Cove all the surface inequalities are montonnées, the striæ running north-northwest. We returned to Trenton bridge by the western shore, having thus skirted the whole island.
Before closing these remarks I wish to allude, in passing, to some other facts connected with this investigation, which I could not easily notice at an earlier time without interrupting my narrative. East and south of Bangor there are considerable deposits of faintly laminated clays, used for the manufacture of bricks, in which striated pebbles and patches of sand are sparsely interspread. I take it for granted that the clays are morainic materials remodelled by the floods arising from the melting of the great glaciers, and the pebbles and sands the droppings of icebergs floating upon these waters. This is the more probable, since accumulations of irregularly stratified sand are always found in the vicinity of such masses of sifted clays, containing scratched pebbles. I have seen similar deposits in the Western States, for instance, near Milwaukee and Chicago.
Between Bangor and Mount Desert the usual evidence of glaciation is very extensive. I would mention as particularly interesting the hills south of Holden and the hills about Dedham. On the route along Union Bay there are also extensive polished surfaces, especially in the vicinity of Bucksport. Near Ellsworth they are beautifully preserved, and all the eminences are montonnées. At Ellsworth Falls, on both sides of the bridge, there are splendid polished surfaces, with scratches and furrows pointing due north. Between Ellsworth and Trenton, and westward of that meridian, in the direction of Bucksport, there are several longitudinal moraines parallel to one another, running from north to south, composed of large, angular boulders, resting upon ground moraines made up of rounded, scratched pebbles and sand mixed with clay. Such a superposition is utterly incompatible with the idea of currents passing over these tracks. Two miles west of Ellsworth a similar longitudinal moraine runs over the top of the hill, and about one mile farther west there is another, chiefly composed of the coarse Dedham granite. The bottom deposit, upon which these moraines rest, consists of fine sand and loam with scratched pebbles. Seven or eight miles west of West Ellsworth the hills, consisting of clay slates on edge, trending from east to west, are abraded, and upon the polished surfaces of their levelled edges rest two other longitudinal moraines, with angular boulders of Dedham granite, running from north to south, and resting upon an extensive ground moraine containing many smaller rounded and striated boulders. Ten miles west of Ellsworth there is still another longitudinal moraine; but the largest of all these parallel moraines is about three miles farther west, that is, about thirteen miles west of Ellsworth. Half a mile south of Bucksport the clay slates are nearly vertical, and their upturned edges are evenly polished and scratched. These surfaces are partially covered with the mud of the Penobscot River. Similar facts may be traced all the way between Bucksport and Bangor. Everywhere the scratches point due north.
The coast range east and west of Somes’s Sound is divided into a series of hills by transverse valleys, in most of which there are small lakes formed by transverse moraines at their southern extremity. Beginning east, and not counting the less-prominent peaks, we have, first, Newport Mountain; next, Kebo and Green Mountains; then, Jordan Mountain, Bobbey Mountain, Hadlock or Pond Mountain, and Westcot Mountain, all to the east of Somes’s Sound; then follow Dog Mountain, Defile Mountain, Beach Hill, and West Mountain, all on the west side of Somes’s Sound. Denning’s Pond, which I have examined more in detail, lies between Dog Mountain and Defile Mountain. The road along the lake follows the eastern or left lateral moraine of the glacier which once filled its basin; and the lake itself is hemmed in by a crescent-shaped terminal moraine at its southern extremity. The lakes, eleven in number, intervening between the other mountains, are likewise bordered by moraines.
We have thus satisfactory evidence that at an early period of the retreat of the great ice-field covering this continent, when it no longer moved over the highest summits of the land, local glaciers were left in the gorges facing the sea. We have thus traced the glaciated surfaces over the whole width of the State of Maine, and over a part of its length, in a narrow track some hundred miles in extent, from the Katahdin Iron Works to the southern shore of Mount Desert, where they are lost in the ocean. I have, however, suppressed a great amount of evidence which could not easily be presented without maps and sections. I may have an opportunity of publishing what has been omitted on some future occasion. Over this whole region, the glacial characters run due north and south, never deflected except by local causes, ascending, in undeviating rectilinear course, all the elevations, and descending into all the depressions. How is it possible to suppose that floating icebergs would advance over such an uneven country with this steadfast, straightforward march? Instead of ascending the hills, they would be caught between them in the intervening depressions, or, if the land were completely submerged, floated over them. The advocates of the iceberg theory forget also that an amount of floating ice, so much larger than is now annually spreading over the Northern Atlantic, implies a far lower temperature; and with it we have the conditions necessary to cover the mainland with glaciers, instead of simply increasing the field of icebergs. Equally impossible is it to suppose that anything so unstable as water has produced such straight and continuous lines.
Assuming, then, that these phenomena were produced by ice, let me add, in conclusion, that the glacial traces over the State of Maine, and especially between Bangor and the sea-coast, afford means of estimating approximately the thickness of the ice-sheet which once-moved over the whole land, as well as its limitations during a later period, when it had begun to wane. In order to advance across a hilly country and over mountainous ridges rising to a height of twelve and fifteen hundred feet in the southern part of the State, and to a much higher level in its northern portion, the ice must have been several times thicker than the height of the inequalities over which it passed; otherwise it would have become encased between these elevations, which would have acted as walls to enclose it. We are therefore justified in supposing that the ice-fields, when they poured from the north over New England to the sea, had a thickness of at least five or six thousand feet. On a future occasion I shall give an account of the drift phenomena along our Atlantic coast, showing also that at that period the ice-fields were not bounded by our present shore line, but extended considerably beyond it, over surfaces now occupied by the ocean. At a later time, during the shrinking and gradual disappearance of the ice-sheet, the ice, no doubt, retreated within the shore-islands. The aspect of the coast of New England must then have been very similar to that of Greenland in its colder portions. Mount Desert itself must have been a miniature Spitzbergen, and colossal icebergs floated off from Somes Sound into the Atlantic Ocean, as they do now-a-days from Magdelena Bay.
This is the second part in a two-part series. Read part one here.
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