cordially agree. I never could see any sound stratigraphical reason why the strata in the Elgin country that have yielded Hyperodapedon, Telerpeton, and Stagonolepis should be separated from the Old Red Sandstone. The piece of Lias (or Oolite as it used to he called) at Linksfield, to my mind, does not alter the question. Mr. Geikie, in a letter lately received, has no doubt that it is a large erratic ice-borne mass. In Northamptonshire Professor Morris has described a larger erratic mass of Oolite, 380 yards in length, exposed in a cutting in Boulder-clay on the Great Northern railway *. I have seen it, and can vouch for his accuracy. Mr. Judd has since discovered several such masses of erratic Marlstone, some of them even of larger size, in the same county, associated with Boulder-clay, and resting indiscriminately on Oxford Clay, Inferior Oolite, and all the formations between. These I have also seen†. The whole mass near Elgin, which has been largely quarried, seems to me to be of the same nature as the great Marlstone and Oolitic erratics observed by Professor Morris and Mr. Judd. If the Hyperodapedon of the Trias is nearly allied to a living lizard, it may very well be equally allied to a lizard of the Old-Red-Sandstone period. In like manner Teleosaurian Crocodilia go down from our times to Liassic or even to Permian times. There can surely, then, be no difficulty in carrying the former two stages lower, to the strata in which Stagonolepis and Telerpeton occur, and which I still believe to be true Old Red Sandstone ; for, as Professor Huxley has well remarked, there is no " necessary relation between the fauna of a given land and that of the seas on its shores‡. This applies to geological time as well as to geographical space.
In conclusion, so vast a continental period as that between the close of the Silurian and the end of the Triassic epochs must have witnessed many disturbances of strata, and changes of physical geography, though the actual identity of the continent was not obliterated thereby. I will only give one comparatively modern instance to show how a continent may become changed, but still remain the same continent, notwithstanding great physical alterations involving upheaval of mountains and the formation of great lakes. From Upper-Eocene times to the present day it is certain that a great part of what is now Europe has existed as a continent ; and yet the Alps and the Pyrenees have to a great extent been raised since that time ; and many vast Miocene fresh lakes in various countries, with a marine interstratification in Switzerland, have been spread across the plains. These also have disappeared, because their consolidated sediments have since been raised in places into mountains.
Finally let me rapidly pass in review what I think we know of terrestrial as opposed to marine epochs in the British and neighbouring areas of Europe.
- Quart. Journ. Geol. Soc. vol. xix. p. 317.
† See Brickenden on the Boulder-clay near Elgin (Quart. Journ. Geol. Soc. 1851, p. 291), C. Moore on the so-called Wealden Beds at Linksfield, &c. (ibid. 1860, p. 445), and A. Geikie on the phenomena of the Glacial Drifts of Scotland (extracted from the Transactions of the Geol. Soc. Glasgow, 1863, p. 48).
‡ On Hyperodapedon (Quart. Journ. Geol. Soc. 1869, vol. xxv. p. 149).
