« PreviousContinue »
generally, and to be independent of chorographic or typographic changes, and have hence been still further denominated UNIVERSAL FORMATIONS.
M. Werner has since, however, been induced to add to these a SIXTH class, consisting of what he has called PARTIAL or LOCAL FORMATIONS: Comprising those which are so often found in vast hollows or basins of particular countries; the materials of which are, in many instances, strangely intermixed, and have probably been carried down into such basins by circumscribed deluges, produced by an exundation of rivers or seas, occasionally alternating with each other, or by other partial disruptions. We have here, therefore, reason to expect-what in fact is perpetually met witha motley combination of whatever substances may have existed in the course of such seas or rivers or rifted soils, with masses or fragments of most of the UNIVERSAL FORMATIONS, alternate beds of marine and fresh-water alluvions, and, consequently, animal and vegetable remains of all kinds.
The composite rocks that fill up the great basin around Paris, in which the skeletons of so many unknown animals, even quadrupeds of the hugest size, elephants, hippopotami, tapirs, mammoths, and other pachydermatous, or thick-skinned monsters, have been discovered, are of this LOCAL FORMATION. The celebrated quarries of Æningen, on the Rhine, are of a like kind; and these, having been erroneously regarded of the same antiquity as Werner's UNIVERSAL FORMATIONS, have been appealed to by various writers as affording proofs of the falsity of his theory.*
*For an admirable defence of this part of the theory, see
We have other instances of this local formation in many parts of our own country, and particularly near the banks of the Thames. Mr. Trimmer has given an interesting account of the substrate of two fields in the vicinity of Brentford, that are loaded with the organic remains of the larger kinds of quadrupeds; as bones of elephants, approaching to both the Asiatic and the African species; horns of deer, apparently as enormous as those dug up in Ireland; bones of the bos genus; and teeth and bones of the hippopotamus; the last very abundant, and intermixed with fresh-water shells*, and other fresh-water relics.
Occasionally, however, marine remains are found intermingled with such animal fossils, and composing their beds instead of those of fresh-water ; and not unfrequently layers of the one kind, as in the basin of Paris, are irregularly surmounted by layers of the other. But no human skeletons are discovered in the midst of any of these rocks, although the bones of man are as capable of preservation as those of any other animal: the only known instance of this sort being that imported into our own country from Guadaloupe by Sir Alexander Cochrane, and which is now exhibited in the British Museum, imbedded in a block of calcareous stone; a very accurate description of which has been published in the Philosophical Transactions by Mr. König.
Mr. Jameson's essay "On Formations," inserted in the Annals of Philos. No. iii. p. 191.
* Phil. Trans. for 1813, p. 135. See also Mr. Webster's valuable essay on the same subject, in vol. ii. of the Transactions of the Geological Society.
It is hence thought highly probable, if not certain, that the catastrophes which involved these enormous quadrupeds in destruction must have occurred at a period when mankind had no existence in the regions which were thus overwhelmed; and in some places overwhelmed alternately by disruptions and inundations of sea and of fresh water. And it is equally probable, that, as the fossil bones are not rolled or violently distorted, or deprived of their natural contour, such remains have not been brought to their present beds from a distance; but that the deluge must have been sudden, and overtaken them in their natural resorts; and hence may, in many cases, have swept away all the individuals of a species in a common calamity.
There is, however, a great difficulty with some naturalists in conceiving that such animals as the elephant, the tapir, the rhinoceros, the hippopotamus, the mammoth, or mastodon, animals now only found in the torrid regions, could have existed in these northern parts of the globe. M. de Marschall endeavoured by one sweeping stroke of the fancy to solve this, as well as that of the extraordinary frag¬ ments in which they are often imbedded, and held out that the whole have fallen at different times, like meteoric stones, from heaven.* The real difficulty, however, vanishes in a considerable degree, if not entirely, when we reflect, that although the torrid regions furnish us with some of these genera, they do not appear in any instance to contain the same precise species as are traced among the large fossil quadrupeds of the northern and colder parts;
* Recherches sur l'Origine, &c. Geissen, 1802.
and hence it is no argument, that because the habits of the extant species do not qualify them for a residence in these latter regions, such situations might not have furnished a comfortable home to the species whose remains are found amongst us. The fossil species do not differ less from the living to which they make the nearest approach, than various animals that are familiar to us do from others that belong to the same tribes, and which are found, under one species or other, over the whole world. The race of horses, of swine, or of sheep, furnishes us with abundant examples of this remark; and that of dogs affords perhaps a still more striking illustration for while under one form, that of the isatis, or Arctic fox, the canis Lagopus of Linnæus, we find it in the northernmost coast of America, and even the frozen sea, living in clefts, or burrowing on the naked mountains, and in that of the almost infinite varieties of the c. familiaris, or domestic dog, in the bosom of our own country,—in the form of the c. aureus, chacal or jackal, we meet with it in the warmest parts of Asia, and Barbary, prowling at night in flocks of one or two hundred individuals.
The extensive TURBARIES or PEAT-FIELDS, which are so common to many parts of Europe, are produced by an accumulation of the remains of sphagnum and other aquatic mosses. These surround and cover up the small knolls upon which they are formed; or, in many places, descend along the valleys after the manner of the glaciers of Switzerland: but, while the latter melt away every year at their lower edges, the mosses are not checked by any obstacle in their regular increase; and as such increase takes place in determinate proportions, by
sounding their depth to the solid ground we may form some estimate of their antiquity.
The ordinary rise of those extensive ranges of DOWNS, DUNES, or DENES, which are seen skirting the coasts of many countries, and especially where the shore is not very bold, is the conjoint effort of sea and wind. To produce this, however, the soil that the sea washes over must consist of sand. This is first pushed in successive tides towards the shore ; it next becomes dry, by being left there at every reflux of the sea; and is then drifted up the beach, and to a considerable distance from the beach, by the winds which are almost always blowing from the sea, and often in whirls or eddies; and are at length fixed by the growth of wild plants, whose seeds are in like manner wafted about on the wings of the breeze, or casually dropped with the excretions of birds or other animals that pass over them. In several parts, observes M. Cuvier, these proceed with a frightful rapidity, overwhelming forests, houses, and cultivated fields in their irresistible progress. Those on the coast of the Bay of Biscay have actually buried a considerable number of villages whose existence is noticed in the records of the middle ages. And even in the present day they are threatening not fewer than ten distinct hamlets with almost inevitable destruction: one of which, named Mimigan, has been in perpetual danger for upwards of twenty years, from a sandhill of more than sixty feet in perpendicular height, produced by the cause we are now contemplating, and which is very obviously augmenting.*
* Report concerning the downs of the Gulf of Gascony, or