Enormous displacements and flexures of the chalk formation have given rise to geological speculation. In illustration we might refer to the beautiful drawings of Mr. Webster, in his letters to Sir Henry Englefield, on the geology of the Isle of Wight. Curvatures in the chalk of the Isle of Purbeck, of extraordinary figure, were first pointed out by the same gentleman. A remarkable mass of chalk appears in the cliff at Trimingham in Norfolk, and is represented in the accompanying sketch. (fig. 122.) It would appear that this was a portion stripped and uplifted from the original horizontal mass; and, if we can judge from the flexuous arrangement of its numerous bands of flints, has been folded by prodigious force into the form of a boulder, on a gigantic scale; its length being seventy, and its height twenty, yards. The surf has considerably reduced its dimensions, but it is still a conspicuous object to the mariners, its white outline being relieved against the dark blue clay in which it is embedded; and, as it is somewhat more indurated than the surrounding mass, it forms a small headland. In all the cases of stratification we have endeavoured to illustrate, their derangements must have taken place subsequently to their original formation. Some of these strata were apparently disturbed while the mass retained sufficient flexibility and adhesion of its parts, to assume those distorted forms without fracture; others were not disturbed until after the entire consolidation of their materials, and present only angular fractures and disrupted planes. It cannot be doubted that the deposition of most of the ancient strata took place, while the waters from whence they subsided were in a comparative state of quiescence. Of this fact, the fine preservation of the most delicate shells, and other organic bodies affords unequivocal testimony. Of a different character, however, is that accumulation of heterogeneous materials, which often forms a thick covering over the regular strata, and has obtained the name of diluvium, as resulting from that catastrophe which so greatly modified the face of our earth. It is impossible to conceive any thing more strongly indicative of the tumultuous action of prodigious currents than those deposits display. On the Norfolk coast, where they arrive at their greatest thickness, an abundance of characteristic sections are exposed. The following (fig. 123.) was sketched in 1824, and shows part of the cliff, about 100 ft. high, west of Cromer. We might multiply illustrations of diluvial contortions, to any extent, were it essential. They consist of concentric layers of sand, gravel, clay, and chalk, or of irregular beds of each, and occasionally exhibit enormous boulders of chalk, and fragments of rocks. At Beeston, on the same coast, may be observed another singular section, whence the following sketch (fig. 124.) is taken. In both cases, the whole reposes upon crag. 124 Crag chalk. Our geologists have scarcely decided whether the ferruginous sands of the eastern counties, containing the marine shells, locally termed crag, should be arranged as appertaining to this great diluvial deposit; some considering it as proper diluvium, while others are inclined to view it as a distinct marine formation, covered by diluvium, and reposing its southern portion upon the London clay, and its northern immediately upon the chalk. Without adverting further to that point, we sub join two sections of its beds, for the purpose of augmenting our illustrations of stratification. 125 The above (fig. 125.) represents a common form in the disposition of the layers. In these cases, the horizontal divisions appear to indicate a succession of eras, or periods of deposit; the intermediate beds are frequently arranged in oblique planes. The site is near Orford, Suffolk, where the crag forms a coarse sandstone, containing several fossil sponges, and is used as a soft building material. The following sketch (126.) is from the ferruginous shelly crag of the caverns near Languard Cottage. 126 Having, by the foregoing series of illustrations, prepared the way for a better consideration of the Weald, we shall introduce the reader to this district, in the words of Mr. Martin. (Geol. Mem., p. 9.) These will be rendered more intelligible by the annexed plan (fig. 127.) which has been reduced from the Geological Society's map, in preference to the less accurate one which accompanies the Memoir. "It must be well known to every traveller who has crossed this valley, that, upon descending from the chalk hills in any part of its western extremity, he enters upon a tract of sandy country, occasionally rising into considerable eminences, and of very varied agricultural aspect. From thence he descends still farther into extensive, woody, and cultivated districts of clay soil, and of exceedingly undulating surface. Traversing this clay country, locally called, and by notoriety, the proper Weald,' he emerges again across the same sand to reach a range of chalk hills, similar to those he left behind him. In the eastern part of the valley, the same series is observed, with the difference, that the sands immediately below the chalk are not so prominent, and the middle of the clay country has a greater intermixture of sandy lands, not destitute of picturesque beauty, but of inferior agricultural character. "The space thus comprised has otherwise, in geological language, got the name of the Weald Denudation;' because there is every reason to believe, from the uniformity of the structure of the valley, and the regularity and peculiar disposition of its chalk boundaries, that the chalk itself, in all its subordinate strata, with perhaps some others often found incumbent upon the chalk, have been once continued over it from side to side (all uniting to form a high table-land, but a small part of a greater expansion of the same materials), and of which it has since been stripped or denuded. "To explain better what is understood by this denudation, or stripping off of the chalk strata, let the reader imagine a plain of chalk, covered or not with other lands of a kindred nature, extended over a part of France, and continued without interruption to the north of England. Let him then suppose, that, looking from above the Alton Hills, he sees the chalk, with its accompanying strata, rent asunder; part sinking southward, to give a bed to the English Channel, from the race of Portland to Beachy-Head (leaving some fractured portions standing, to tell the story of convulsions), part northward, to form the south side of what is called the London basin, from Marlborough Downs to the Straits of Dover. "Let him also suppose, that, whilst this is in progress, and all the immense intervening masses are fissured and crumbled by convulsion, a flood of water, powerful beyond comprehension, at the same instant, or immediately after, rushing over, and entering the broken surface, sweeps the whole contents of what is now the weald excavation before it, into the North Sea itself but a part of the abyss just then opened, perhaps by the same concussion, to receive them. "Or, let cer A change come o'er the spirit of his dream, Let him suppose this part of our island lifted up out of the ocean by an impelling power from below, some parts of it more steadily and evenly, others with such irregular and successive heavings, as to produce the effects above spoken of; disruption of the central parts, and such fissuring and rending of the circumference, as an irregular action is calculated to produce upon a ponderous and frangible material. "Such a dream, splendid as it may be, will fall far short of the reality of those changes that can be demonstrated to have taken place in parts of the world, well understood to be more ancient than these under consideration. "If the mind is staggered at the immensity of such an operation, let it be answered, that the Weald Valley is but a small furrow on the earth's surface. And let our thoughts revert for comparison to many greater natural phenomena; to the height of the Himalaya, which may be well supposed to have felt the power of the same ocean stream, perhaps to have been lifted out of it, or to the five miles of depth, which may be given to that ocean; and then consider how small a proportion the aggregate ten miles holds to the diameter of the globe itself. "Nothing is great, nor nothing little, in the operations of nature; and such disclosures as these sink into insignificance before the wonders of astronomy! The mind is lost in the contemplation of the immeasurable power to which it is indifferent, that 666 'Now a bubble bursts, and now a world."" Without entering into the detail of the strata beneath the chalk, which are exposed by the Weald denudation, it will be sufficient here to state that they are recognised by the names of malm-rock, or green sand, the gault or blue marl, and the upper ferruginous sand, all of which are now classed by the author under the comprehensive term glauconite. Beneath this occurs |