118 CJironicles of Science. [Jan., 



believe ttat during the two latter periods our country passed through 

 conditions of glaciation as severe as it has done during the Post- 

 PHocene period. Mr. CroU, however, argues that sulmerial denuda- 

 tion, by destroying the whole of the land surfaces, has effectually 

 removed all direct proof, although the indirect evidence is vciy much 

 in favour of their occurrence. From calculations based upon the 

 amount of sediment brought down by the Ganges, Mississippi, and 

 other rivers, it would follow that from the close of the Miocene and 

 Eocene Glacial periods to the present day, supposing the rate of 

 deposition to be constant, 120 feet and 410 feet respectively have 

 been removed and carried down to the sea in the form of sediment. 

 The cosmical theory of climate also requires that if glacial condi- 

 tions obtained at these periods, warm and equable climates must 

 have prevailed immediately before or after them, and the author 

 maintains that this is just what has happened. In the Turin 

 Miocene, conglomerates considered glacial by Sir C. Lyell are 

 overlain and underlain conformably by strata indicating a sub- 

 tropical condition of climate. The same phenomena are also observed 

 in Switzerland in rocks of the Middle Eocene jieriod, where we find 

 " flysch " closely associated with nummulitic strata, which contain 

 genera characteristic of a warm chmate. The Cretaceous and 

 Permian periods afford similar evidence, and in the Post-Pliocene 

 glacial period we have undoubted proof of a warmer climate during 

 part of its duration, as evidenced by the occurrence of animals and 

 shells existing in latitudes where they could not otherwise have 

 lived in consequence of the cold. Space will not permit us to follow 

 Mr. Croll any farther, but we would refer those of our readers who 

 are interested in the subject to the paper itself, which will well repay 

 a careful perusal. * 



The Woolhope Naturalists' Field Club is fortunate in having for 

 its head-quarters a typical district in British geology, and it has, so 

 far, taken advantage of its position as to publish in the new volume 

 for the year 18G7 two papers by the Ecv. R. Dixon, — one on the 

 "Geology of the Woolliope District," and the other on "Upper 

 Silurian Fossils." The Woolliope district i^resents, according to 

 Murchison, one of the best examples of a valley of elevation in the 

 British Islands, and has even been referred to by Humboldt as an 

 instance of the result of what he calls " Vulcanicity." By a continued 

 volcanic action, the Uj^per Llandovery Sandstone has been upheaved 

 some 9000 feet from its original position, into a dome-shaped mass, 

 exposing on its flanks the superjacent rocks, which underlie the Old 

 Pied Sandstone. Fossils from the various beds are very numerous, 

 and it was from the Woolliope Limestone of this district that the 

 new Orthoccratite {Aciinoceras haccatiim), described by Mr. H. Wood- 

 ward in a recent number of the * Geological ]\Iagazine,' was obtained. 

 The paper is accompanied by a list of the chief localities where the 



