100 The Lower Ceetaceous Floras of the World 



the last edition of De Lapparent are generally understood and are used 



in the present discussion: 



ALBIAN (d'Orbigny 1842) (Gault) 



r Gargasian (Kilian 1887)' 

 APTIAN (d'Orbigny 1842)= | Be^oulian (Toucas 1888) 



{includes the Urgonian (d'Orbigny 

 1850) and the Rhodanian (Rene- 

 vier 1854) 



NEOCOMIAN (Thurmann 1835) = ( Hauterivian (Renevier 1874) 



1 Valanginian (Desor 1854) 



As a step in the preparation of the chapter on correlation the various 

 Lower Cretaceous floras have been tabulated, and since they present much 

 that is of interest the following abstract seems worthy of publication. 

 ISFo attempt has been made to completely revise authors' identifications, 

 and a number of minor papers have been omitted. After sketching 

 briefly what is known of these floras a brief analysis is attempted. 



The etages JSTeocomian, Urgonian, Aptian, and Albian we owe largely 

 to the genius of d'Orbigny. Since the massive limestones of the Ur- 

 gonian at Orgon, in the lower valley of the Durance, represent such a 

 local type of sedimentation and fauna, French geologists have advocated 

 the substitution of the term Barremian, from Barreme in the Basses 

 Alpes, for this stage, which is also sometimes made an upper division 

 of the Neocomian. 



With regard to the term Wealden which occupies such a prominent 

 place in geological literature it is quite certain that it represents a phase 

 dependent upon the physical conditions accompanying deposition, which 

 obviously may have been inaugurated at slightly different times in differ- 

 ent areas, and which may have persisted longer in some areas than in 

 others. Its use should therefore be dissociated from the idea of a 

 chronologic unit and restricted, if used at all, to the stratigraphic unit 

 represented by deposits of this type. 



^Kilian in Freeh, Lethsea geognostica, 2 Teil, 3 Band, Kreide, 1 Abt., 

 Palaeocretacicum, 1907. 



= Subcretaceous (Gumbel 1881), Eocretaceous (De Lapparent) Palaeocre- 

 taceous (Kilian 1907). 



