Mr Ward in his book on the Geology of the English Lake District, while describing some of the effects that various rock formations have on scenery, has stated that the mountains surrounding Lake Derwentwater are not only geologically interesting, but are very beautiful. To quote his own words. He says: ‘If we take our stand upon Friar’s Crag, jutting out into Derwentwater, we have before us one of the fairest views that England can give. The lake, studded with wooded islets, and surrounded by mountains of varied form and outline. Upon the west side, the mountains, most exquisitely grouped together, have soft outlines and smooth and grassy slopes, sometimes meeting below to form, as in Newlands Vale, an inverted arch of marvellous elegance and grace. These are of Skiddaw slate, which mostly weathers away in small flakes or pencil-like pieces, giving rise to a clayey and shaly wash at the base of the hills. Upon the east side of the lake and at its head, the case is otherwise; the mountains have generally rough and hummocky outlines and steep and craggy sides; whilst their waste lies below in the shape of rough tumbled masses, like ruins of a giant castle. These consist of rocks belonging to the volcanic series, which are hard, massive, and well jointed. Thus we have presented to us two independent types of scenery, formed by very distinct classes of rock.’
Southey, in a letter to Coleridge, describing the view from his house (Greta Hall), compared the mountains of the first type above mentioned to the ‘tents of a camp of giants;’ whilst it is between a rift in the rocks of the latter, or volcanic series, that the Watendlath burn rushes down and forms the picturesque Falls of Lodore.
But, apart from the varied charms of scenery surrounding Derwentwater, and the many historical reminiscences connected with the immediate neighbourhood, the lake has a phenomenon of its own in the so-called Floating Island. The visitor to Keswick may see at any time, and if such be his desire, may row round and thoroughly inspect four islands on the lake; but this one, through its somewhat eccentric movements, is not so easily examined. In fact, it only exists as an island for a few weeks’ duration, and then generally at intervals of several years. The last time it was visible was in 1884, when it was noticed about the middle of August; and disappeared during the first week in October. It is doubtful whether all the causes of this occurrence are yet known; for, on its last appearance, considerable interest was taken in it by scientific men, and several experiments were made with a view of ascertaining its substance, both solid and gaseous. Certain it is that, even in these days of accurate information and universal reading, considerable misconception must exist on the subject. For instance, an article appeared in this Journal for August 1874, in which it was stated that ‘until it was driven ashore in a gale, a few years ago, there used to be an island of this kind’ [the writer had previously spoken of a floating island on a Swedish lake, which occasionally sank below the surface and reappeared] ‘on Derwentwater, Cumberland.... When a stick or fishing-rod was driven through it, a jet of water would spurt up from the hole; thus indicating that some spring or current was pressing against it from below; and this was probably the force which kept it at the surface, and being of an intermittent character, allowed it at times to sink to the bottom.’ This writer’s idea was, that a waterfall, which he mentions as ‘throwing itself into the lake,’ but is in reality at least a quarter of a mile off, caused a current, which, according to its force, was able to buoy the island up by its pressure. This fallacious theory is mentioned in one or two guide-books to Keswick, one stating that, ‘the guides, the older and more intelligent ones, will tell you of a little stream that gets lost in the ground.’ This ‘little stream’ is the Catgill Beck, which, in its passage from the hills, forms the waterfall spoken of in the previous quotation. The ‘driven ashore in a gale’ statement is easily refuted by the fact that the island made its appearance two years after in the same place as on its previous emergences, namely, about a hundred and fifty yards from the shore at the south-eastern corner of the lake.
The Daily News of August 20, 1884, contained a short leading article on the subject, in which, after describing the floating gardens of the ancient Mexicans, the writer continues: ‘This at Derwentwater seems to be merely an accidental accretion of material round some tree-trunk or something of the kind, which, as in the larger island just alluded to [an American one], has become in some way anchored to the bed of the lake, probably at that point not very deep.’
The writers of the two articles above quoted could never have examined, and probably had never even seen the island in question.
A frequent source of error is the notion people are liable to carry away who have only seen it from the shore. Many see it, probably for the first and only time, from the top of a stagecoach, on their way to Buttermere or on some other favourite excursion. Just previously, the driver has perhaps directed their attention, by a jerk of his whip over his left shoulder, to Raven’s Crag. Now, there is a gap in the trees on the other side, and a glimpse of the lake is caught. ‘Floating Island,’ laconically remarks Jehu to the box-seat occupants, and again points his whip, but this time to the right towards the lake. ‘Where? where?’ ask the others behind. ‘There, there—don’t you see?’ and on rolls the coach, some wondering if that little patch of green were it; others, failing to see anything, refer to their guide-books or companions as to what object of interest must next be looked for. Lodore Hotel comes into view, and the minds of the hurried tourists are once more engaged in a hasty examination of the Falls. So the day wears on, and they have seen the Floating Island. But how, and how much? Even the name itself may cause misapprehension, although it would be difficult to give the object a more definite appellation.
The island is not mentioned either by Hutchinson or Nicolson and Burns in their Histories of Cumberland, published towards the end of last century. In an interesting account, however, of A Fortnight’s Ramble to the Lakes, by Jos. Budworth, F.S.A., published 1795, a short reference is made to it. After speaking of the ‘stormy breakers’ on the lake, caused by ‘a bottom wind,’ he goes on to say: ‘It is said Keswick Lake often wears this appearance a day or two previous to a storm; and when violently agitated at the bottom, an island arises, and remains upon the surface some time.... The grass and the moss are as green as a meadow, which soon unite and become consistent. There are very few people in the neighbourhood who have not been upon it.’ It is probably to Jonathan Ottley, a native of Keswick, and a very careful observer, that we owe the first really authentic account of the island. In a paper read before the Manchester Literary and Philosophical Society, and published in their Transactions for the year 1819, he gives a graphic description of it, and mentions a newspaper correspondence having appeared in the Carlisle Journal some years previous, in which two or three different theories were propounded by various writers as to the cause of its emergence. At the end of this Memoir, a note from John Dalton—the author of the Atomic Theory, and a native of Cumberland, although at this time he had resided in Manchester for some years—explains, that ‘being at Keswick in 1815, Mr Ottley and I procured a small quantity of the gas [from the island], which I found to consist of equal parts of carburetted hydrogen and azotic gases, with about six per cent. of carbonic acid.’ It will be seen from the above that the island had not escaped the observation of men of science very early in the present century.
From a distance, it looks like a grass plot floating on the lake. It is never more than six inches above the water, but varies considerably in area in different years. On its last emergence, the exposed surface was about fifty yards by twelve; but in 1842 it was upwards of ninety yards long by twenty broad. It generally makes its appearance in July, August, or September, and disappears towards the end of the last month. In 1831, however, it came to the top on the tenth of June, and remained exposed until the twenty-fourth of September—the longest period ever remembered. It has never been seen except in the summer or autumn months, and then only after periods of excessive drought and warm weather; but whether its origin is owing to the lowness of the water in the lake, or to the high temperature, or to a combination of both causes, is still an open question.
The bed of the lake where the island appears consists of what, were there no lake over it, would be called a peat-moss, which extends over several acres. When the water is calm, dark-brown patches may be seen over the whole of this area, indicating rents or fissures. The depth of water is very uniform here, varying from six to eight feet when the lake is at an average height. The appearance of the island is caused by a portion of this peat-moss rising, not bodily, as in a detached mass, but like a huge blister. It is this peculiar manner of rising that upsets the preconceived notions of many visitors, leading some to suppose that the surface of the lake having become lowered, through drought or other causes, a portion of its bed has been laid bare. Although this peat-moss is capable of considerable distention, owing to the elasticity of its component parts, it not unfrequently occurs that a rupture takes place whilst rising to the surface. In such cases, two islands are sometimes formed, but more frequently one part sinks, when a fairly accurate idea may be formed of the thickness of the peat-moss or substance of the island. If the second portion, or part that has remained at the surface, on resuming its position at the bottom, does not exactly fill the same space as before, a gap is caused, which accounts for the apparent dark patches before mentioned.
The aquatic plants growing on the bed of this portion of the lake are, when living, all specifically lighter than water, which may easily be proved by detaching any of them from the bottom, when they will be found to rise to the surface. They grow, wither, and decay, their roots matting together amidst the finely divided turf, itself the remains of various mosses, producing what Ottley aptly calls a ‘congeries of weeds.’ The thickness of this mass is about six feet, and rests upon a bed of clay. After a continuance of high temperature, the air and gas—of which there is always a considerable amount in such substances—expand. This expansion is sufficient to reduce the weight of the whole slightly below an equal volume of water. The water insinuates itself between the peat-moss and the bed of clay on which it rests, but to which it is in no way attached, owing to the roots not being able to penetrate it. The mass slowly rises, the lighter portion gradually dragging itself to the surface, although, as has been previously stated, not absolutely detaching itself from the rest. After appearing above the level of the water, the weeds make vigorous growth, which tends to reduce temporarily the specific gravity of the whole still more, and to give that emerald hue to the exposed part which made Budworth describe it as being ‘as green as a meadow.’ If, through heavy rainfall, the water-level of the lake be raised, the island rises and falls with it. Should low temperature, however, supervene, the mass loses its buoyancy, and slowly disappears; once more to sink into obscurity and become part of the bed of the lake, after having, for a butterfly existence, basked under the warm August sun as the Floating Island.