From the well-known quarries in Portland, a description of which would tempt us too far astray, have been procured the materials for St. Paul’s Cathedral, the Reform Club, and other public buildings. A visit to Portland, and examination of the quarries, such as we have twice paid, is well worth the attention of any summer tourist, and will richly repay, in its romantic scenery, and in the unique simplicity of its people’s manners, a week’s quiet stay at the King’s Arms, the once favoured and favourite inn of George the Third.
Then, if we take the middle oolite, we shall find in it the well-known “coral rag,” so called because of the continuous beds of petrified coral found in great abundance, and in many places, apparently, in the same position in which they once grew at the bottom of the sea. We give below a few specimens recently obtained by us from the north of Wiltshire, from which it will be seen how closely they resemble those of existing species.
OOLITE CORAL. (Nat. Size.)
CORALS AND SPONGE FROM THE OOLITE.
But what period was that, and what sunny clime was this, when the ocean poured its waves over what are now our oolitic building-stones, and when the coral insect built its continuous reefs in this our England, just as it is now distributing its labours over so vast an expanse of sea in the tropics and the southern hemisphere?[[90]] We cannot but recal the poetic and vivid language of Hugh Miller: “Oh, that hoarse voice of Ocean, never silent since time first began!—where has it not been uttered? There is stillness amid the calm of the arid and rainless deserts, where no spring rises and no streamlet flows, and the long caravan plies its weary march amid the blinding glare of the sand; and the red unshaded rays of the fierce sun. But, once and again, and yet again, has the roar of Ocean been there. It is his sands that the winds heap up, and it is the skeleton remains of his vassals,—shells, and fish, and the stony coral,—that the rocks underneath enclose. There is silence on the tall mountain peak, with its glittering mantle of snow, where the panting lungs labour to inhale the thin bleak air, where no insect murmurs and no bird flies, and where the eye wanders over multitudinous hill-tops that lie far beneath, and vast dark forests that sweep on to the distant horizon, and along long hollow valleys, where the great rivers begin. And yet, once and again, and yet again, has the roar of Ocean been there. The effigies of his more ancient denizens we find sculptured on the crags, where they jut from beneath the ice into the mist wreath, and his later beaches, stage beyond stage, terrace the descending slopes. Where has the great destroyer not been,—the devourer of continents—the blue foaming dragon, whose vocation it is to eat up the whole land? His ice-floes have alike furrowed the flat steppes of Siberia, and the rocky flanks of Schehallion; and his nummulites and fish lie embedded in the great stones of the Pyramids, hewn in the times of the old Pharaohs, and in the rocky folds of Lebanon still untouched by the tool. So long as Ocean exists, there must be disintegration, dilapidation, change; and should the time ever arrive when the elevatory agencies, motionless and chill, shall sleep within their profound depths, to awaken no more, and should the sea still continue to impel its currents and to roll its waves, every continent and island would at length disappear, and again, as of old, ‘when the fountains of the great deep were broken up,’
‘A shoreless ocean tumble round the globe.’”[[91]]
From this digression we return to our third division of the Oolite proper, the Lower Oolite, as developed in Somersetshire (around Bath), and in Wiltshire (Tisbury, Braford, &c.), which has its own points of interest and of use. Here occurs the fuller’s earth, mostly found at a village near Bath, called Old Down, which possesses the peculiar property of absorbing the grease or oil remaining in cloth, and thus fulling or thickening it. Here also is found that peculiar rubbly limestone, called “Cornbrash,”[[92]] in Wiltshire, which, on exposure to atmospheric agencies, soon decomposes, and by mixture with he ordinary constituents of the soil, makes an admirable material in agricultural operations. Here also we have the Bath Oolite, the quarries of which are very extensive, abundant in fossils, and the character of whose stone gives to the city of Bath that clean and aristocratic appearance which is so striking to the stranger approaching Bath from the Great Western Railway.
“In this lower division,” says Lieutenant-Colonel Portlock, “also occurs the Bath oolite, which is an excellent stone for the delicate mouldings of gothic architecture, and is represented in France by the Caen stone, which was imported for the purpose by our early architects, as may be seen in the beautiful Temple Church.”[[93]] Of two varieties of Oolite, called “Barnack rag” and “Ketton stone,” obtained from the quarries in Rutlandshire and Northamptonshire, almost all the churches in Cambridgeshire, of the twelfth and thirteenth centuries, are built. As an instance, and illustrative of previous remarks, we may specify King’s College Chapel, Cambridge. Whoever has been to the top of that gem of gothic architecture, and walked outside where the stone is weathered, and has been supplemented in various indifferent ways, may there see the ripple marks of the old tides and winds, marking the ebb and flow of pre-Adamite phenomena; and little shells, some of them most tiny ones, but in beautiful preservation, once left in the soft calcareous sand, now embedded in the hard building stone. And here, before we speak of the fossils of the Oolite, we should like to be thoroughly understood about this same ripple-mark, of which we have more than once spoken, and which it seems desirable to explain. “Another structure, often conspicuous in fine-grained sandstones, is that commonly called “ripple-mark.” Either in quarries or natural cliffs, wherever the upper surface of a bed is exposed, it is often found to be not smooth or flat, but waved in small undulations, exactly like those so often seen on a sandy shore. Now, a good deal of misconstruction has, I think, arisen as to the origin of these small undulations or ripples in the sand, leading sometimes to a possibility of grave error in geological reasoning. People standing on the beach, and observing the gentle rippling motion of the waves, and a very similar form in the sand beneath them, have not unnaturally jumped to the conclusion that the one was the cause of the other, that the ripple on the surface of the water had somehow imprinted its form on the sand at the bottom. Now, really, one is not the cause of the other, but they are both caused by the same action, and each is as much a ripple as the other. The wave-like form in the sand is not a ripple mark, but a ripple; if it is the mark of anything, it is a ‘current mark,’ and as such I have always preferred to speak of it. Just as a current in the air produces a ripple in the surface of the water below it, so a current in the water produces a ripple in the sand below it. It makes no difference, indeed, whether the sand be acted upon by air or water. Wherever the circumstances are favourable, wind will cause a ripple or current mark on the surface of blown sand, as I observed frequently under very favourable circumstances at Sandy Cape, in Australia, and as has been observed by Sir Charles Lyell, near Calais. In each case the moving fluid propels the grains of sand forward, piling them up into ridges, which are perpetually advancing by the rolling of particles over the crest of each ridge into the hollow beyond, where they are for a time sheltered from the current, but soon buried under the advancing ridge, to be again turned up and rolled onward, perhaps, as their site becomes exposed to the force of the stream.”[[94]]