Mr. Lyell's Researches in North America. 563 



CucuUaeffi of the greensand, though in some more recent publications 

 the Faversham fossil has been considered identical with the Cucul- 

 lasse of Blackdown. 



TERTIARY ROCKS. 



An important addition to our knowledge of the relations of the 

 Tertiary rocks of Europe proceeds from the pen of Mr. Lyell. On 

 comparing the fossils of the Faluns of the Loire with those of the 

 Cotentin, and again, by a comparison of both with the crag of Suf- 

 folk, Mr. Lyell has corrected a view which he had formerly adopted, 

 that these deposits were not formed during the same epoch. By 

 an attentive examination of different tertiary localities in Normandy, 

 some of which seem to have escaped the notice of former obser- 

 vers, he has ascertained the existence of many of the true Suffolk 

 crag fossils in deposits extending southwards as far as Sainteny. 

 He then describes the Faluns, properly so called, at Dinan, Rennes, 

 Nantes, Angers, Done, Sevigne, and the tracts S. and S.E. of Tours, 

 in some of which the great abundance of corals and echinoderms, 

 and the small number of mollusks, present a perfect analogy to the 

 white or coralline crag of Suffolk, though the fauna is quite distinct 

 in species from the fauna of the coralline crag. From the existence 

 of a number of detached points of Faluns, Mr. Lyell infers that a 

 large part of France, now drained by the Loire and its tributaries, 

 was submerged during the Miocene period. Finally, he convinces 

 himself that all the shells of these French deposits belong to one 

 group, and that they are really contemporaneous with the crag of 

 Suffolk, though there may be shades of difference in their relative 

 ages. It is well to observe that so sound a geologist as Mr. Lyell 

 does not shrink from identifying two distant deposits in which eighty- 

 five per cent, of the fossils are of distinct species, fifteen species 

 only being found common to the two, because he shows that both 

 these deposits correspond exactly in the analogy which they bear 

 to the fauna of the present day. Having also detected freshwater 

 and land remains in the intervening tract, Mr. Lyell further offers 

 us a satisfactory explanation of how the Miocene Faluns of the Loire 

 and our Suffolk crag should be contemporaneous deposits and yet so 

 different in contents, the seas in which they were respectively accu- 

 mulated having been separated by dry land ; that in which the crag 

 was deposited opening to the north, and those in which the Faluns 

 were accumulated opening to the south. 



Mr. Lyell's works being before us, I seize this opportunity of con- 

 gratulating the Society that a geologist possessing his powers of 

 classification should now be occupied in studying the structure of 

 North America. In that wide field, in which for the last few years 

 the native observers have been gathering together botli a vast pro- 

 fusion of valuable detailed sections, as well as many general com- 

 parisons with our own divisions, it is impossible that a good Euro- 

 pean geologist can fail to reap an abundant harvest ; and whether 

 it be "in his own tertiary domain, of whidi he has so largely ex- 

 tended our knowledge, or by grai)pling with the Palajozoic rocks, 

 whicii in that vast continent arc developed on so splendid a scale, 



