300 Geological Societj/. 



periods, in which the existing forms of animated nature seem one 

 after another to disappear. 



Twenty years are not yet passed away since MM. Cuvier and 

 Brongniart first published their researches on the geological struc- 

 ture of the Paris basin. The innumerable details exhibited in their 

 various essays ; the beautiful conclusions drawn from unexpected 

 facts ; the happ}' combination of mineralogical and zoological evi- 

 dence; the proofs of successive revolutions, till then unheard of, 

 in the physical history of the earth — all these things combined, 

 not merely threw new light on a subject before involved in compa- 

 rative darkness, but gave new powers and new means of induction 

 to those who should in after times attempt any similar investiga- 

 tions. 



Mankind are, however, dazzled and astonished by great disco- 

 veries, as well as guided and instructed : and for some years after 

 the publication of these admirable works, the naturalists of various 

 countries, whose attention had been so loudly called to the deposits 

 above the chalk, saw in them only a repetition of v/hat was already 

 described, and of which the true type was in every case to be sought 

 among the formations of the Paris basin. Investigations conducted 

 in this spirit sometimes ended in disappointment. But this was not 

 the spirit recommended in the incomparable Essaj^ of Cuvier*; for 

 after exhibiting the true method of geological induction, and de- 

 scribing the intense and almost tormenting interest with which he 

 had followed out his own investigations, he points to the long series 

 of deposits in the Sub-Apennine hills, and states his conviction that 

 in them lies concealed the true secret of the last operations of the 

 ocean. 



Since that discourse was written, much has been done ; but much 

 more still remains to be done. It has been my pleasing task to place 

 before you the labours of some of our own body in illustrating the 

 recent geological periods in the history of the earth : by such de- 

 tails alone can we expect to comprehend the more intricate phaeno- 

 mena of still older periods, and to connect them with the great phy- 

 sical laws by which all matter is governed. 



Considered in the most general point of view, without any re- 

 gard to the lacustrine beds, which are perhaps local or acciden- 

 tal, the tertiary groups of the Paris basin may be described as a 

 great complex system of deposits, belonging to one protracted zoo- 

 logical period ; characterized by extinct genera of mammalia, and 

 by innumerable marine shells; but affording ver}' few species by 

 which we can connect them either with the chalk, or with the for- 

 mations of our neighbouring seas. Their position is therefore en- 

 tirely insulated ; and by what new links they may be connected with 

 the physical events which went before them and followed after them, 

 can only be determined by a long series of observations. I Iiave 

 already pointed out the source from which some of the older links 

 may hereafter probably be supplied. Of the same palaeotherian 

 age, and in the same insulated position, are the tertiary deposits of 



* See Dlscours Piclimiiiairr, p. 112, 1st edition. 



Hampshire, 



