reviewing all the statements published previously to my late tour for and against the reality of the change of level in Sweden, that my scepticism appears to have been unwarrantable; but it will not be disputed that too many proofs cannot be accumulated to substantiate so remarkable a phenomenon.

I propose, therefore, to lay before the Royal Society the observations which I made during the summer of 1834, with a view of satisfying myself in regard to the data appealed to in support of the elevation of parts both of the eastern and western shores of Sweden. As much of the evidence could only have been derived from personal intercourse with the inhabitants, it may be proper to mention that I was accompanied throughout my excursion by a well-informed Swede, Mr.JOHNSON, who by his thorough knowledge of the English language was well qualified to assist me as interpreter.

On my way to Sweden I examined the eastern shores of the Danish islands of Möen and Seeland; but neither there, nor afterwards in Scania, could I discover any signs of a recent upward movement of the land, nor could I learn that the notion of such a change was entertained by the natives. Proceeding northwards along the ⚫ coast of the Baltic, the first place which I visited where any elevation of land is supposed to be going on was Calmar. This port is situated in latitude 56° 41'. To the south of the town is the celebrated ancient castle in which was signed, in the year 1397, the famous treaty of union between Sweden, Denmark, and Norway. The castle is supposed to have remained in its present state from a still earlier period. There was a fortress on the site so long ago as the year 1030*. Two round-towers terminate the outworks of this fortress on the side of the sea; and when I observed that the base of one of these rested on the beach only two feet above the level of the water, and when I found that sea-weed had recently been washed up, so as to touch the lowest part of the building, I concluded, at first, that for the last four or five centuries there could have been no lowering of the Baltic at this place, for otherwise we should be compelled to suppose that part

Fig. 1.

Part of one of the round-towers of Calmar Castle. of the tower had been originally constructed under water. But on nearer inspection I was led to suspect that this had really been the case, and that the foundation was originally subaqueous. At the height of about two feet above the base of the tower (see sketch, fig. 1.), and four feet above the level of the sea, a projecting band of stone (a), one foot deep, encircles the tower like a hoop. This projecting band is of smooth stone, and the stones above it are large, and with an even, dressed surface. But below the hoop are many courses

Sea

a

a, Projecting band or hoop of stone; b, thin layers of slabs of stone and mortar, originally perhaps built under water; c, the beach covered by water when the sea is high.

of thin slabs of a different stone (b), with layers of cement between. It oc

*See ANKARSVARD'S Work on Calmar Castle.

curred to me that these rough slabs and cement may have been laid originally under water, and that the projecting rim of dressed stone may have formed the visible base of the building, which now rises to the height of about twenty-five feet above. This idea is rendered the more probable, as it is known that the castle had often defended itself from attacks on the side of the sea. I have since been informed by our eminent architect Mr. WILKINS, that it is highly probable, from the general analogy of buildings having a subaqueous foundation, that the courses of slaty stone were laid under water, and that the projecting fascia was alone intended to be seen above the level of the sea. Admitting this conjecture to be well founded, it would still prove that there has been a much slighter rise of the land since this building was erected, or during the last four centuries and upwards, than some writers have imagined, for it cannot have amounted to more than four feet in that time. Part of the moat on one side of the castle, which is believed to have been formerly filled with water from the sea, is now dry, and the bottom covered with green turf. It may have been in part silted up with sand and sediment, but a slight rise of the land would have contributed to its desiccation. A garden, composed of newly gained land in the harbour, between the castle and the town, in a place where there was sea half a century ago, clearly shows that the deposition of sedimentary matter may sometimes take place rapidly on this coast.

From Calmar I went to Stockholm, where I immediately found many striking geological proofs of a change in the relative level of land and sea, since the Baltic was inhabited by the same species of Testacea which it now supports.

The country around Stockholm is in general low, seldom rising to more than 150 feet above the level of the sea, the fundamental rocks being gneiss and granite, which are often quite bare, presenting a surface for the most part smoothed and rounded, as if these rocks had formed for a long time the bottom of the sea, and had been worn and almost polished by the continual attrition of sand and pebbles. A mass of shingle and sand, here and there passing into loam, occasionally covers the rock; but it is rarely of great thickness, excepting along certain lines, where remarkable ridges of sand and gravel are seen, called in Sweden sand-oasar (åsar), the term 'oas' in Swedish corresponding to 'rigging' in Scotch, and for which we have no precise English synonym. These oasar are immense banks of sand, from fifty to several hundred yards broad, and from fifty to more than one hundred feet in height, which may often be traced in unbroken lines for a great many leagues through the country, but are breached occasionally by narrow transverse valleys. They usually run in a direction from north to south; generally terminate on both sides in a steep slope, and are sometimes so narrow at the top as to leave little more than room for a road. As they afford excellent materials for road-making, a great many of the highways in Sweden are carried either along the summit or base of these ridges, so that the traveller has many opportunities of observing their form and structure. In places where they are composed of large rounded boulders, of about the size of a man's

head, no stratification is observable; but where, as is more usual, they consist of gravel and fine sand, they are invariably stratified, in the same manner as sand and gravel in the beds of rivers. A great succession of thin layers repose one upon another, often at high inclinations. But this disposition can only be seen where there is a fresh section made in digging for gravel, the materials being so loose as to fall down and soon form a sloping talus.

I shall offer, in another place, some speculations on the probable origin of these ridges; and I have merely alluded to them now in order to explain the position of some fossil shells which I am about to describe. I had learnt from Professor NILSSON, of Lund, a gentleman well known to geologists by his valuable work on the fossils of Scania, that marine shells of species similar to those in the Baltic had been found near Stockholm; and soon after my arrival I was taken to the spot by Professor BERZELIUS. They occur at Solna, about a mile to the north-west of the city, at the foot of one of the great ridges of sand and gravel before mentioned; a ridge which, passing southward, traverses the city of Stockholm, and is said to have afforded fossil shells in the large pits at the Skantstull, in the southern suburbs.

The annexed section will show that there is little more than space for the road between the ridge and the gravel-pits at Solna.

These pits lie between the church of Solna and the public cemetery of Stockholm. Both in the pits and in the adjoining ridge the gravel and sand is stratified, and in general no organic remains can be discovered in them; but in the pits, a little below the level of the road, there are some layers of loam mixed with vegetable matter, where shells occur in abundance. They consist principally of Cardium edule and Tellina Baltica, a great number of which have both valves united. Portions of the Mytilus edulis also occur; and there has evidently been a great accumulation of this shell in the stratum, but it is almost entirely decomposed, and is only recognized by the violet colour which it has imparted to the whole mass. The other shells which I found are, Littorina crassior, also the Common Periwinkle (Littorina littorea), and a small Paludina allied to, if not identical with, our English Paludina ulva (see Plate II. fig. 5.). The Mytilus and Cardium are all dwarfish in size, just as they are found in the brackish water of the neighbouring Gulf of Bothnia, and the whole assemblage of shells is such as characterizes the Baltic. The bed containing them has been ascertained by Colonel HÄLLSTROM to be thirty feet above the level of the Baltic;

so that they afford a clear indication of a change in the relative level of that sea to the amount of thirty feet since its waters were inhabited by the existing species of Testacea. On inquiring whether any other examples had been observed of similar deposits of shells, I was informed by Colonel HÄLLSTROM that he had discovered them on the farm of Orby, near Bränkyrka, about three miles to the south of Stockholm. He obligingly accompanied me to the spot, where I found strata of marl and sand filling the bottom of a valley situated in a broken tract of ground where the fundamental rock is gneiss. This tract of land intervenes between Lake Maeler and the sea.

The shells are very numerous, and are for the most part imbedded in a peaty soil containing fragments of wood. The peat has perhaps been derived from sea-weed, large accumulations of which I saw recently heaped up in a bay of the Baltic near Sölvitzborg, intermixed with similar species of shells. The identity of the shells of Bränkyrka with those of the neighbouring sea was even more complete than at Solna; for in addition to the species before enumerated, I found the Neritina fluviatilis, a freshwater shell which lives in abundance in the brackish waters of the Baltic, and which I saw covering the rocks in the saltish water at Gräsö, near Oregrund. The Baltic variety is small, and usually black; but both in the recent and fossil individuals it sometimes exhibits its usual variety of colours. Some specimens also of a land shell (Bulimus lubricus) occurred with the marine at Bränkyrka.

The height of these shells has been determined by Colonel HÄLLSTROM to be seventy Swedish feet above the Baltic; so that they indicate a fall of the waters, or rather a rise of the land, to that amount, since the neighbouring gulf was inhabited by this assemblage of Testacea. But the most remarkable spot where these Baltic shells occur in a fossil state is still further to the south, at Södertelje (see the Map, Plate I.), about sixteen miles south-west of Stockholm, where they are found elevated more than ninety feet above the sea. At Södertelje a canal was cut in 1819 across a barrier of sand, gravel, and clay, which separated Lake Maeler from a long narrow inlet or frith of the Baltic. The canal is, in fact, carried through the bottom of one of those valleys so common in this district, of which the sides consist of rocks of gneiss, and the bottom of the same covered by more recent deposits. The accompanying transverse section (fig. 3.) will explain this geological structure.

Section across the valley of Södertelje, showing the position of the new deposits in relation to the gneiss. The boundary hills of bare rock rise to the height of two hundred feet, the newer formation being in some places about one hundred feet high, while on others, as on the site of the Lake Maren, there are hollows which sink beneath the level of the sea.