boulders of Saie Harbour, given in the next page, may be referred to as interesting in reference to the above remarks on the conglomerate, admirably shown in the locality alluded to.

On the beach at Grouville Bay, south of the extreme point at which the conglomerate is found, there are also chalk-flints in large numbers, but generally smaller and fragmentary. The proportion of such pebbles is, however, still very large. The conglomerate behind and near St. Catherine's Harbour dips about 30° E.N.E.; and this dip is constant for a distance of more than half a mile. The extreme limit of the deposit seems to be from the middle of St. Catherine's Harbour to the easter: side of Bouley Bay, a distance, in a direct line, of rather more than three miles.

The precise geological age of this conglomerate being at present undetermined, and the beds dipping considerably and for the most part to an easterly quarter, it is possible that there may be some connection between them and the Alderney sand-stone There is, indeed, nothing in common between the two, beyond this general relation to a north and south axis of elevation lifting up the islands through an angle of about 30°. That the Alderney sand-stone is on the north and east of that island, and the Jersey conglomerate on the south and cast of Jersey, suggests the possibility that the principal east and west axis lies betwee the two, and agrees with the position of Guernsey and Sark These obscure connections, traceable between the islands, introduce hypotheses that may help to direct future enquirers. They can hardly be regarded at present as more than suggestive; but if it should appear that the Alderney sand-stone and the newer conglomerate are contemporaneous, the older Jersey conglome rate may, perhaps, belong to the Cherbourg grits.

At a point behind St. Catherine's, and again on the dese of the carriage-road to Bouley Bay, there are small deposits of a very fine red sand-stone, with clayey bands. These depos's are nearly horizontal, and are no doubt modern, but there »

FREQUENT UPHEAVALS OF LIMITED EXTENT.

275

nothing in them to mark their precise date. They are situated far above the present level of the sea, and must have been deposited before or during the last great elevation.

It becomes, then, quite certain, whatever we may decide as to older disturbances and original elevation, that numerous movements of upheaval, of different amounts and in different directions, have affected the Channel Islands at various times. It is also certain that many of these have been such as to affect each island differently, thus proving the limited extent of the elevating action in such cases; for, had it been large, it must have affected uniformly the comparatively small area containing all the islands and the surrounding sea.

Many details have been omitted in this sketch of the crystalline and metamorphic and other older rocks of the Channel Islands, but the outline given may, perhaps, be useful and suggestive. Let us pass on now to the modern deposits, the recent changes of level, and the recent destruction of the coast.

CHAPTER XI.

GEOLOGY AND MINERALOGY OF THE CHANNEL

ISLANDS.

MODERN DESTRUCTION AND RENOVATION.

THE magnificent scenery, so much admired on the coast of all the Channel Islands; the wild desolation that reigns when the receding tide lays bare needle points, or exhibits alternate floors and walls of granite, in places where a few hours ago the water presented a smooth, but treacherous surface; the broken cliffs, detached headlands, natural arches and recesses, and gloomy caverns; the grotesque rocks, some prominently jutting out, some fallen from above and angular, some rounded and smooth; -all these are the results of an action of wind and water that is going on every year, winter and summer, and that is always tending to reproduce, with little essential variety, the very forms and outlines it is constantly destroying. Scenery representing these picturesque appearances, is pictured with great accuracy in many of the illustrations in this volume.* Such

The views in the present
Title to Part III., befver

* See more especially the following views:-Cliff and Roche Pendante in Alie ney, Chapter I. Gouliot Rock in Sark, Chapter II. Various views of Jersey it Chapter III. The Corbiere in Guernsey, Chapter X. chapter. The Burons, Chapter XII. The rocks in the Chapter XIII. St. Catherine's Bay, Jersey, Chapter XVIII.; and the Const Scene in Guernsey, Chapter XIX. These have all been selected and drawn wit a special view to illustrate the wild coast scenery of the principal islands.

SUBTERRANEAN FORCES.

277

representations are not the less valuable because in a few years they must refer to things of the past, for there will still be in the same, or some near place, a similar specimen of rock scenery, produced on similar material by identical causes.

To understand the secret history of the picturesque in these islands, it was necessary that the nature and origin of the rocks should be in some measure learnt, and in the last chapter it has been attempted to give a brief outline of these. It remains now to consider the modern changes, the forces now at work, and the result of their combined agency in our own, or very recent times.

In all this, however, we must speak in geological language. What is meant by modern and recent, is very old in comparison with human records, and dates back to a time, when, if men existed, they belonged to races long extinct; races, whose only remains hitherto found are fragments of broken flint or harp stone, wherewith savages might perform those few actions that proclaim their human intellect.

The modern influences we allude to in this chapter are several; they include subterranean movements, producing slow upheaval or depression of large tracts; the destroying and reproducing action of the waves in breaking up hard rocks, and accumulating the debris at a distant point; the action of rain and changing temperature; and the action of organic life, modifying in various ways the inorganic forces.

That there are forces of the kind just mentioned, the reader, not accustomed to geological investigations, must take for granted. Proofs of them exist in abundance; but it would involve explanations not justified in a work of this kind, to present them to the reader. They are readily found and all the results mentioned are every day events in nature.

Assuming then that the syenites and porphyries of the Channel Islands, covered, perhaps, at one time, with numerous and thick deposits, have been slowly brought into their present position,

the sea all the time acting on the uprising mass, and clearing away the softer matter, so as to bare and denude the surface, we may imagine a time when the various operations were less advanced than at present, when the lands were larger, and when they were more nearly connected with the continent.

The first class of changes we have mentioned, includes those resulting from subterranean movements of elevation or depres sion. One of the most familiar illustrations of the existence of such forces is seen in the earthquake, a phenomenon common enough in various parts of Europe, and not unknown in these islands. Many have been recorded within the last thousand years, and many more of smaller magnitude have certainly taken place.

In the History of Guernsey, by Mr. F. B. Tupper, it is stated that an earthquake of serious magnitude, producing great destruction, took place in the month of March, 709, and another, or rather a series of movements, between the 22nd and 29th October, 842. On the latter occasion, there was throughout the north of Gaul an accompanying subterranean noise, lasting seven days, recurring several times a day. Afterwards, in the year 1091, very severe and disastrous shocks were felt in the islands, and at Angers, on the Loire, stones were thrown from the arches of the windows of the large tower of the church. Two years before there had been serious concussions in England, and in 1161, the whole shore of the Cotentin was disturbed, the islands being also greatly affected. There are no records of disturbances in the islands from that time till 1813; but, for several centuries, shocks were so frequent, and the mischief done by them so notorious in England and in France, that there can be little doubt the intermediate sea-bottom must have been affected.* At the

There is a curious notice in a MS. in the British Museum, apparently reter ring to a severe earthquake shock in the sea off Sark, that must have occurred st the close of the seventeenth century. The year 1691 was remarkable for severe earthquake action in the Atlantic.