v Cuvier and Brongniart on Paris Basin 219 



marine sandstones, an unfossiliferous siliceous limestone, 

 and a sandstone formation without shells, Cuvier and 

 Brongniart found a widespread fresh-water siliceous lime- 

 stone or millstone, specially characterised by containing 

 Limnea, Planorbis, and other lacustrine shells. 



The youngest formation which they described was the 

 alluvium of the valleys, with bones of elephant and trunks 

 of trees. 



Subsequent research has slightly altered and greatly 

 elaborated the arrangement made by Cuvier and Brong- 

 niart of the successive Tertiary formations of the Paris 

 basin. But although the subdivision of the strata into 

 definite stratigraphical and palseontological platforms has 

 been carried into far greater detail, the broad outlines 

 traced by them remain as true now as they were when 

 first sketched early in the century. These two great men 

 not merely marked out the grouping of the formations in 

 a limited tract of country. They established on a basis 

 of accurate observation the principles of palseontological 

 stratigraphy. They demonstrated the use of fossils for 

 the determination of geological chronology, and they paved 

 the way for the enormous advances which have since 

 been made in that department of our science. For these 

 distinguished labours they deserve an honoured place 

 among the Founders of Geology. Cuvier's contributions 

 to zoology, palaeontology, and comparative anatomy were 

 so vast and important that his share in the establishment 

 of correct stratigraphy is apt to be forgotten. But his 

 name must ever be bracketed with that of Brongniart 

 for the service rendered to geology by their conjoint work 

 among the Tertiary deposits of the Paris basin. 



