At the meeting of the British Association in 1865, Mr. Pengelly, in a paper on “The Insulation of St. Michael's Mount in Cornwall,” maintained that the change which converted that Mount from a promontory into an island must have taken place, not only within the human period, but since Cornwall was occupied by a people speaking the Cornish language. As a proof of this somewhat startling assertion, he adduced the ancient British name of St. Michael's Mount, signifying the Hoar rock in the wood. Nobody would think of applying such a name to the Mount in its present state; and as we know that during the last two thousand years the Mount has been, as it is now, an island at high, and a promontory at low tide, it would indeed seem to follow that its name must have been framed before the destruction of the ancient forest by which it was once surrounded, and before the separation of the Mount from the mainland.
Sir Henry James, in a “Note on the Block of Tin dredged in Falmouth Harbor,” asserts, it is true, that there are trees growing on the Mount in sufficient numbers to have justified the ancient descriptive name of “the Hoar rock in the wood;” but though there are traces of trees visible on the engravings published [pg 318] a hundred years ago, in Dr. Borlase's “Antiquities of Cornwall,” these are most likely due to artistic embellishment only. At present no writer will discover in St. Michael's Mount what could fairly be called either trees or a wood, even in Cornwall.
That the geographical change from a promontory into a real island did not take place during the last two thousand years, is proved by the description which Diodorus Siculus, a little before the Christian era, gives of St. Michael's Mount. “The inhabitants of the promontory of Belerium,” he says (lib. v. c. 22), “were hospitable, and, on account of their intercourse with strangers, eminently civilized in their habits. These are the people who work the tin, which they melt into the form of astragali, and then carry it to an island in front of Britain, called Ictis. This island is left dry at low tide, and they then transport the tin in carts from the shore. Here the traders buy it from the natives, and carry it to Gaul, over which it travels on horseback in about thirty days to the mouths of the Rhone.” That the Island of Ictis, described by Diodorus, is St. Michael's Mount, seems, to say the least, very probable, and was at last admitted even by the late Sir G. C. Lewis. In fact, the description which Diodorus gives answers so completely to what St. Michael's Mount is at the present day, that few would deny that if the Mount ever was a “Hoar rock in the wood,” it must have been so before the time of which Diodorus speaks, that is, at least before the last two thousand years. The nine apparent reasons why St. Michael's Mount cannot be the Ictis of Diodorus, and their refutation, may be seen in Mr. Pengelly's paper “On the Insulation of St. Michael's Mount,” p. 6, seq.
Mr. Pengelly proceeded to show that the geological [pg 319] change which converted the promontory into an island may be due to two causes. First, it may have taken place in consequence of the encroachment of the sea. This would demand a belief that at least 20,000 years ago Cornwall was inhabited by men who spoke Cornish. Secondly, this change may have taken place by a general subsidence of the land, and this is the opinion adopted by Mr. Pengelly. No exact date was assigned to this subsidence, but Mr. Pengelly finished by expressing his decided opinion that, subsequent to a period when Cornwall was inhabited by a race speaking a Celtic language, St. Michael's Mount was “a hoar rock in the wood,” and has since become insulated by powerful geological changes.
In a more recent paper read at the Royal Institution (April 5, 1867), Mr. Pengelly has somewhat modified his opinion. Taking for granted that at some time or other St. Michael's Mount was a peninsula and not yet an island, he calculates that it must have taken 16,800 years before the coast line could have receded from the Mount to the present cliffs. He arrived at this result by taking the retrocession of the cliffs at ten feet in a century, the distance between the Mount and the mainland being at present 1,680 feet.
If, however, the severance of the Mount from the mainland was the result, not of retrocession, but of the subsidence of the country,—a rival theory which Mr. Pengelly still admits as possible,—the former calculation would fail, and the only means of fixing the date of this severance would be supplied by the remains found in the forests that were carried down by that subsidence, and which are supposed to belong to the mammoth era. This mammoth era, we are told, is anterior to the lake-dwellings of Switzerland, and the [pg 320] kitchenmiddens of Denmark, for in neither of these have any remains of the mammoth been discovered. The mammoth, in fact, did not outlive the age of bronze, and before the end of that age, therefore, St. Michael's Mount must be supposed to have become an island.
In all these discussions it is taken for granted that St. Michael's Mount was at one time unquestionably a “hoar rock in the wood,” and that the land between the Mount and the mainland was once covered by a forest which extended along the whole of the seaboard. That there are submerged forests along that seaboard is attested by sufficient geological evidence; but I have not been able to discover any proof of the unbroken continuity of that shore-forest, still less of the presence of vegetable remains in the exact locality which is of interest to us, namely between the Mount and the mainland. It is true that Dr. Borlase discovered the remains of trunks of trees on the 10th of January, 1757; but he tells us that these forest trees were not found round the Mount, but midway betwixt the piers of St. Michael's Mount and Penzance, that is to say, about one mile distant from the Mount; also, that one of them was a willow-tree with the bark on it, another a hazel-branch with the bark still fat and glossy. The place where these trees were found was three hundred yards below full-sea mark, where the water is twelve feet deep when the tide is in.
Carew, also, at an earlier date, speaks of roots of mighty trees found in the sand about the Mount, but without giving the exact place. Lelant (1533-40) knows of “Spere Heddes, Axis for Warre, and Swerdes of Copper wrapped up in lynist, scant perishid,” that had been found of late years near the [pg 321] Mount, in St. Hilary's parish, in tin works; but he places the land that had been devoured of the sea between Penzance and Mousehole, i.e. more than two miles distant from the Mount.
The value of this kind of geological evidence must of course be determined by geologists. It is quite possible that the remains of trunks of trees may still be found on the very isthmus between the Mount and the mainland; but it is, to say the least, curious that, even in the absence of such stringent evidence, geologists should feel so confident that the Mount once stood on the mainland, and that exactly the same persuasion should have been shared by people long before the name of geology was known. There is a powerful spell in popular traditions, against which even men of science are not always proof, and is just possible that if the tradition of the “hoar rock in the wood” had not existed, no attempts would have been made to explain the causes that severed St. Michael's Mount from the mainland. But even then the question remains, How was it that people quite guiltless of geology should have framed the popular name of the Mount, and the popular tradition of its former connection with the mainland? Leaving, therefore, for the present all geological evidence out of view, it will be an interesting inquiry to find out, if possible, how people that could not have been swayed by any geological theories, should have been led to believe in the gradual insulation of St. Michael's Mount.
The principal argument brought forward by non-geological writers in support of the former existence of a forest surrounding the Mount, is the Cornish name of St. Michael's Mount, Cara clowse in cowse, which in Cornish is said to mean “the hoar rock in the wood.” [pg 322] In his paper read before the British Association at Manchester, Mr. Pengelly adduced that very name as irrefragable evidence that Cornish, i.e. a Celtic language, an Aryan language, was spoken in the extreme west of Europe about 20,000 years ago. In his more recent paper Mr. Pengelly has given up this position, and he considers it improbable that any philologer could now give a trustworthy translation of a language spoken 20,000 years ago. This may be or not; but before we build any hypothesis on that Cornish name, the first question which an historian has to answer is clearly this:—