162 T. Davidson — On Continental Geology. 



earth, then the heat thus conveyed might to a considerable extent 

 compensate for the absence of ocean-currents, and land at the equator 

 might in this case be nearly as well adapted as water for raising the 

 temperature of the whole earth. But such is not the case ; for the 

 heat carried up by the ascending current at the equator is not em- 

 ployed in warming the earth, but is thrown off into cold stellar space 

 above. This ascending current, instead of being employed in warm- 

 ing the globe, is in reality one of the most effectual means that the 

 earth has of getting quit of the heat received from the sun, and of 

 thus retaining itself at a mtich lower temperature than it would other- 

 wise be. It is in the equatorial regions that the earth loses as well 

 as gains the greater part of its heat. So of all places it is here that 

 we ought to place the substance best adapted for preventing the dis- 

 sipation of the earth's heat into space if we wish to raise the general 

 temperature of the earth. Water, of all substances in nature, seems 

 to possess this quality to the greatest extent; and, besides, it is a 

 fluid, and therefore adapted by means of currents to carry the heat 

 which it receives from the sun to every corner of the globe. "^ 



VI.— Notes on Continental Geology and PALiEONioLOGT. 

 By Thomas Dayidson, F.E.S., F.G.S. 

 (Part I.) 



RECENT considerations of health having induced me to sjjend 

 from five to six months on the continent, I beg to submit to 

 the readers of the Geological Magazine the result of my notes 

 made during my journey, which may perhaps prove not entirely 

 uninteresting. 



I. On the Cretaceous System. — All the foreign geologists with whom 

 I have had occasion to converse in France, Switzerland, and Italy, 

 concur in the opinion that no country has been better studied than 

 Great Britain, and that the Museum of the Geological Survey and 

 its published Maps are unsurpassed by any works of a similar kind 

 hitherto produced.^ 



Our geologists have done their work well, and justly deserve the 

 favourable judgment so liberally bestowed upon them by their 

 continental colleagues ; but we must not therefore suppose that our 

 geological work is perfected and that we have no more to learn — • 

 for example — that our classification of British strata is either com- 

 plete or entirely satisfactory. It is absolutely necessary we should 

 know and compare the labours of continental observers with our 

 own and see whether their discoveries or hints might not lead us to 



1 Trans, of Glasgow Geol. See. vol. ii. part iii. p. 185 ; Phil. Mag. Feb. and June, 

 1867. 



2 See " De la Science en France " by Jules Marcou, 1869. This work, to which I 

 would call the attention of British geologists, is being published in numbers, and treats 

 of the Imperial School of Mines, the Geological Map of France, the Academy and 

 Institute of France, and of the Museum of Natural History in Paris, and may be 

 obtained from C. Reinwald, Bookseller, 15, Eue des Saint Peres, Paris ; or through 

 Messrs. Triibner & Co. 



