206 DISCUSSION OF THE DESICCATION QUESTION. 



of land surface during the Carboniferous epoch, not only in North America, 

 but in parts of Europe. This fact, like most of the others connected with 

 the formation of coal, and especially that of this particular epoch, is exceed- 

 ingly difficult of explanation. It does not, however, seem to the writer to 

 militate against the general result stated above, namely, that the land masses 

 have, on the u'hole, been gaining in area during the successive geological 

 ages. 



As an excellent illustration of this, reference may be made to Delesse's 

 maps showing the areas occupied bj' land in France during the successive 

 geological epochs.* On examining these, it will be seen at once that, on the 

 wliole, the gain of land surface in that country, from one epoch to another, 

 has been most decided. This has been especially the case since the begin- 

 ning of the Cretaceous period. There was a rapid diminution in the area 

 occupied by the ocean, over the region now included within the limits of 

 France, from the Eocene period on. At the beginning of the Pliocene there 

 were still extensive lacustrine areas covered by fresh or brackish water, all 

 of which, however, entirely disappeared before the end of that epoch. 



This sequence of geological events is best seen in the case of a country 

 like France, where the series of formations is remarkably complete, and the 

 recent orographic disturbances not so general and so intense as to obscure 

 the relations of the various groups. In regions, like that of Northeastern 

 North America, where there are immense gaps in the geological series, 

 similar conditions as to the increase of land surface with the lapse of time may 

 exist, although not so easily recognized b}' an inspection of the map. We 

 have, however, in this region a very decided predominance of marine sti-ata 

 in the earlier formations, and great and perhaps, in some regions, sudden 

 gains of land surface at several successive epochs. Indeed no one can for 

 a moment doubt that, taking the areas occupied by the present continents 

 into consideration, land has been, on the whole, gaining upon the sea most 

 decidedly. 



This indeed seems to be the natural order of things, if simplicity be ad- 

 mitted to be more natural than complexity. Granting that the surface of 

 the globe, in consequence of unequal shrinking while cooling, assumed an 

 irregular form, so that portions were elevated, more or less considerably, 

 above the level of the ocean, then, supposing no farther change of the 



* Maps accompanying the " Lithologie des Mers de France, et des Mers Principalcs du Globe, par II. 

 Delesse." Paris [1871]. 



