around the base of the tree, and regular layers of peat moss and forest vegetation had accumulated above the roots during the long period of its growth.

During this period of four hundred years it would appear that the bog added only six inches to its depth. As far down as the charcoal layer there is no great difference in the nature of the bog deposit; sometimes an extra amount of forest mould shows that the trees which grew along the borders of the bog were able to throw out colonies into the open sphagnous area; at others a return of a moister climate reversed the conditions, and the bog encroached on the forest; but assuming that the growth was comparatively uniform, twelve hundred years would have elapsed from the time when the charcoal layer was deposited until the seed of this cedar sprouted in the moss of the bog.

But in estimating the age of the charcoal layer, other factors are to be considered; one of these is the condensation of the peat in the lower layers by the weight of the superincumbent mass of vegetable matter. To test this, a sample of the peat above the roots of the cedar tree was weighed and compared with that of the peat a foot down from the surface; the latter was found to be a third heavier, showing a considerable condensation of the mass; at a lower level the weight was still greater. Allowing for the reduction of bulk from this cause in the lower layers, I think it may be assumed that 2,000 years have elapsed since the charcoal layer was deposited, and therefore since the occurrence of the forest conflagration of which it is a witness.

THE ROCK FORMATION OF THE BERMUDAS.

By J. S. BUCHAN, Q.C., B.C.L.

A few preliminary remarks concerning the Bermudas generally may be of interest, and will assist in making the special subject before us more clearly understood.

The Bermudas are a cluster of islands about 350 in number, many being, however, mere rocks, situated in the Atlantic Ocean in Lat. 32° 20' N. and Long. 74° 50′ W., or, to describe their position in other words, a straight line 700 miles long, drawn almost due south from Halifax, would pass through them, while another due west, about 600 miles in length, would almost strike Charleston in South Carolina.

The islands lie to the south of a coral reef or atoll about 24 miles in length by 12 in breadth, of which the part above water is the southern fringe or edge, containing in all only about 19 square miles of land, and said to be, with the exception of St. Helena, the most isolated body of land on the globe.

They form the only coral reef in the Central Atlantic, and almost the only instance in which living, reef-building coral is found so far to the north, the conditions being, however, favorable to it, owing to the temperature of the water being raised by the Gulf stream.

The surface of the islands presents a succession of low, rolling hills, with valleys between them, and scarcely any level ground, the highest point being Gibb's Hill, on which the light-house is situated, 362 feet above sea level. The soil, of a red-brown color, is only a few inches deep, but very fertile.

The islands are altogether of coral formation, which is found in various stages, from the sand thrown up by the waves to the stalagmite which marks the floor of some ancient cave from which the roof and walls, with the hill in which it was formed, have been swept away.

The process by which the final stage, if it may be so called, is reached, is not only of great interest in itself, but particularly so because it is now, as it has doubtless been throughout the whole history of the islands, going on, and can be studied in all stages of progress.

The beginning of this process must be sought for in the reefs which surround the islands, and protect them from the direct force of the sea. Out on the reefs, where the coral is living and growing, fragments are constantly broken off and thrown in towards the shore by the violence of the surf, to be by the same means gradually ground up into a fine sand, which is eventually washed up to form a beach, wide stretches of which are exposed at low water.

From this point the evolution of the rock formation may be said to begin. The sand is blown inland by the wind, forming great ridges, which have the appearance of enormous snowdrifts. The principal "sand-glacier" where this is now to be seen is at Elbow Bay, on the south shore, where the sand has drifted far inland to great depths, completely filling up valleys, and even overwhelming houses in its progress. The whole of the land has been formed in the same manner, as in some of the quarries a stratum of the red surface soil is sometimes seen under 30 or 40 feet of more recent rock, formed by the sand drifting over the land surface, and then becoming consolidated.

The first stage in the formation of the land is thus reached, when the sand has been piled up into a hill, which continues to grow until it has perhaps assumed a form, which prevents it from continuing to drift in the same direction.

When this stage has been reached, the surface soon. becomes covered with vegetation, and the process towards the next stage begins. The sand by its own weight becomes more compact, especially where the drift is of great depth, and through the action of the rain water per

colating through it, the sandbank gradually changes first into the material shown in the specimen marked No. 1 in the Museum, and in the course of time into the hard crystalline form marked No. 2, which is simply a later, or more advanced form, of the rock under the same process, but appearing more particularly where the pressure has been greatest.

The other specimens, Nos. 3 and 4, are the result of a different action. In many cases, through certain parts of the sand hill being more soluble or less compact than others, cavities are opened, which are enlarged in various ways until caverns are formed, in which the water, percolating through the roof, forms stalactites and stalagmites, in the manner common to all limestone formations, but in the Bermuda caves with great rapidity, owing to the soluble nature of the rocks. For the same reason, whole hills have in some cases been swept away by erosion, or more properly, by the softer parts of the rock becoming disintegrated, and in some cases apparently dissolved by the action of the elements, leaving in places sharp pinnacles, composed of the harder parts of the rock, standing, and in others, the floors of caves covered with stalagmite. The specimen No. 3 was, in fact, taken from such a cave floor on Ireland Island, near the dockyard, and No. 4 from one of these pinnacles, which seem to become cemented together into a quasi-stalactite, and then, when the softer parts disintegrate, it is further hardened by weathering.

This in brief is the process by which the coral rock is formed, which throughout the islands is everywhere the

same.

This rock is of the greatest value to the people, particularly in view of the fact that wood is not available for building purposes, owing to its scarcity. The rock, when in situ, is soft, and easily cut into any shape with ordinary tools. When a quantity of the material is required for any purpose, the soil is removed from a hillside, a large

block cut out of it, which is then sawn into the desired size and shape, and the pieces piled up until they become hardened, which soon occurs when exposed to the action of the sun and the atmosphere.

The blocks and slabs thus obtained form an excellent building material, which is further protected by a whitewash, made from a very strong lime, obtained from the same rock as the building material itself. The islands have excellent roads, which are for the most part cut through the hills so as to leave no gradients, and the surface of which becomes as hard and smooth as ordinary asphalt.

There are no freshwater streams or wells in the Bermudas, and the water supply is obtained altogether from the rains. Every one who erects a dwelling is obliged by law to provide a tank or cistern of a certain capacity, proportionate to the dwelling, the cistern being frequently built in the excavation from which the material for the house was taken, which only required a covering of cement to make it water-tight.

As is frequently the case with coral islands, the Bermudas are steadily sinking, possibly on account of the weight of new material as it is added to them, and this would seem to have been the case throughout their whole exist

ence.

The coral insect appears to be incapable of existing in more than 30, or at most 50 fathoms of water, but even close to the reefs depths of from 12,000 to 15,000 feet are found. From this it would appear that the base of the Bermudas was a great elevation, possibly of volcanic origin, on which the coral insects found a suitable formation to build the reefs from which the islands were formed, and if the Atlantic were drained it would have the appearance of a huge mountain from 2 to 3 miles in height, rising from an almost level plain.

As the building progressed, the mountain continued to