ANNIVERSARY ADDRESS OF THE PRESIDENT. lxix 



the Tertiary districts of Prance and England, and published a table 

 of equivalent strata, showing great ability and sagacity ; but unfor- 

 tunately the data on which the synchronisms are based, both with 

 respect to organic remains and physical structure, are not given. 

 The main points on which M. Dumont throughout insists are the 

 breaks in the sequence, corresponding with certain movements of 

 elevation. The fuller descriptions and lists of fossils were reserved 

 for a larger work, of which unfortunately his early death has de- 

 prived science. A table embodying his most recent views was pub- 

 lished in the Journal of our Society for 1852. 



To the great and extensive deposit of loamy drift which covers 

 so much of Belgium, he applied the term of "Limon Hesbayen," 

 being a portion of his " Systeme diluvien," which again was a section 

 of the " Terrains Quaternaires." The deposits arising from hot 

 springs, evolutions of vapour, and gases, he proposed to designate as 

 of " Geyserian " origin, in contradistinction to rocks of igneous and 

 sedimentary origin. 



It will be observed from the preceding remarks, that, whilst recog- 

 nizing the great value of a purely mineralogical examination of a 

 country, both as regards a correct determination of the true causes 

 of metamorphism and with a view to trace out the physical forces 

 which have contributed towards the present constitution and distri- 

 bution of mineral strata, I have endeavoured to show that no per- 

 fect knowledge of the successive epochs of the earth's history can 

 be acquired without the study of its fossils, or in other words, of its 

 natural history. Neither of these modes of inquiry should be neg- 

 lected, as it is quite evident that any one taken alone can give but an 

 imperfect notion of the whole subj ect. M. Dumont directed his efforts, 

 and they were great and most sldlfully conducted, to the mineral 

 mode of investigation ; but there is little doubt that he would, had 

 his life been spared, have ere long given more attention to the pahe- 

 ontological mode of inquiry, as being the only one which can make 

 the works of the geologist a philosophical history, and not a mere 

 dry account of isolated facts. 



I do not consider it necessary to dwell on M. Dumont 5 s mine- 

 ralogical essays, or on his description of Louisiana; but the paper 

 which he read to the Academy of Brussels on the 22nd November 

 1834 deserves especial notice, as it refers to that much-vexed 

 question, the origin of the volcanic craters of the Eifel. These he 

 enumerates as craters of elevation, craters of eruption, and lake- 

 craters: and he observes that the conical mountains, known in 

 the Eifel as volcanic, have generally no appearance of a crater. They 

 have a circular base, a summit more or less pointed, and tolerably 

 uniform slopes : they are, for the most part, formed on one side by 

 scoriaceous matter, and on the other by inclined beds of compact 

 lava or tephrine, similar to that which extends into the plains in a 

 more or less horizontal sheet, whilst at the foot of the inclined beds 

 is often found a trainee of large blocks of the same description. 

 These conical mountains, M. Dumont calls " cones of elevation", and 

 he explains the facts described in the following manner. The com- 



vol. xiv. / 



