Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/229

 Great Wall, N. lat. 40°, to the neighbourhood of Ningpo, N. lat. 30°, and includes considerable portions of the provinces of Chihli, Shantung, Kiangsu, and Chehkiang ; and the more ancient clay-beds, which form most of the plains of the interior, though even here, from the peculiar formation of the mountain-chains, only occurring in a number of isolated basins, and overlain in portions by the more modern alluvial deposits.

In the valley of Yangtse these older clays divide themselves naturally from their composition into three classes : 1st, the laterite of Kiukiang and its neighbourhood, apparently reaching into Anhwei province ; 2nd, the yellow clays of Anhwei ; and 3rd, the soft calcareous deposits of Kiangsu, well developed in the neighbourhood of Chinkiang. The first seems to rest immediately on gravels, representing apparently those forming the summit of the red sandstone described above (p. 133), these gravels at the foot of the Lu-shan passing into a coarse till containing small boulder-like stones (fig. 2). To these succeed beds of fine sand interstratified with clay ; and over all are found thick deposits of a bright red hard clay, containing numerous vermiform cavities, and apparently precisely similar to the laterite of Southern and Central India. This clay is sufficiently hard to form bold cliffs overhanging the river Yangtse, and is so little affected by the action of water as to form tails of quasi- boulders running out at several points into the river, and very dangerous to navigation.

The second class forms a series of bright reddish, yellow, and grey clays, and is probably only a local variation of the former, as it varies much in appearance in different localities, forming a series of brick and pottery clays, and probably comprehending the famous porcelain clays of Kiangsi ; it occurs in portions of Kiangsu, in Anhwei, Kiangsi, and Hupeh, besides stretching, as there is every reason to believe, to the extreme south and west of China.

Both these clays are distinguished by the almost complete absence of lime in their composition, and both are to a considerable degree ferruginous. I can at present form no idea of their thickness ; but they have undergone in parts very considerable denudation. In the fissures and channels formed in the older limestone rocks by the action of water during previous ages, and up to a height of some hundred feet above the plains, masses of a bright red clay of apparently similar composition constantly occur, though I have not been able to trace the clays themselves for any considerable height ; unless towards the bottom, these clays are unstratified. To this formation I am disposed at present to refer the fossil bones and teeth spoken of above. In South India the laterite has, I believe, been usually referred to the Pliocene age, which would seem to harmonize with the mammalian fossils found in apparently similar deposits in China.

In lower Kiangsu, and notably in the neighbourhood of Chinkiang and Nanking, these older beds are succeeded, apparently unconformably, by a mass of eminently calcareous clays of a pale yellowish brown colour and extremely friable texture, so readily affected