causes of the glaciation or ice-markings of Europe. Nature never works by one means alone, but accomplishes her ends by many agents, all working, each in due proportion, towards the same end. So in these, glaciers have accomplished much, but bergs and sea- ice have also done their part in forming the glacier-remains of Britain and other portions of the world. The fault of all the theorists is to suppose that the means they are advocating — glaciers, bergs, or sea-ice — alone accomplished the end in question. If any one can give me a better explanation, then I will gladly give up my own. Only if my theory is rejected then my facts must be accounted for, and it must be shown how this great deposit of clay, which, as the laws of nature are constant, must have been forming in the glacial epoch, is to be accounted for. There are difficulties in the way ; but as the best theory is the one which explains the greatest amount of appearances most reasonably, and as we can only reason regarding the past from what we see going on at present, I humbly submit there is some degree of truth (at least) in the theory I have ventured to submit.
10. On an Altered Clay-bed and Section in Tideswell Dale, Derbyshire. By Rev. J. M. Mello, M.A., F.G.S., &c.
The object of my present communication is to call attention to an interesting section that has lately been exposed in a quarry on the eastern side of Tideswell Dale in Derbyshire. The locality is exactly pointed out by the words " Tideswell Dale " in the Ordnance Map No. 81, S.E. At this spot it will be seen, by a reference to the map of the Geological Survey, that an outcrop of toadstone occurs. Another outcrop of toadstone is also exposed by the railway-cutting on the right bank of the Wye, opposite Litton Mill ; this rock is fully described in the recently published memoir of the Geological Survey relating to this county. Above this are found thinly-bedded limestones; whilst lower down the river the toadstone is wanting, and a considerable thickness of fossiliferous limestone occurs with " thin lenticular partings of shale and red clay." At the bottom of Miller's Dale a toadstone, capped by about 150 feet of limestone, is seen running along the roadside on the left bank of the river ; this bed up into islands to produce any large bergs. Between the north-east point of Spitzbergen and Greenland there are no icebergs until we reach the Greenland coast, where a few of inconsiderable size are found, no doubt formed in some of the East Greenland fjords. Vide Chydenius, ' Svenska Expeditionen til Spitsbergen, ar 1861, under ledning af Otto Torell,' &c, 1865, for many valuable details on this subject ; and some interesting notes by Mr. James Lamont on Spitzbergen in the ' Quart. Journ. Geol. Soc.' (1860), vol. xvi. pp. 150 & 428. Prof. Torell, of Lund, is at present engaged on this subject ; and from his researches much new light may be expected to be thrown on the glacial remains of Scandinavia, observations regarding which, by many eminent Scandinavian naturalists, have greatly elucidated the subject. Without being invidious, I may cite Sars's ' Jagttagelser over den Glaciale Formation ' (Universitets Program, Christiania, 1860) as being of much value to English students of glacial clays.
