551.77 (44) 193 
V 
The Delimitation of the Albian and Cenomanian 
in France 
HE nomenclature of the English Cretaceous System is based 
upon the lithological differences exhibited by its members, 
the only division which from the beginning ‘had a name of different 
origin being the Wealden. Such a basis of nomenclature is bad 
because lithological differences are local or provincial accidents. 
French geologists have often expressed surprise at the con- 
servatism of Englishmen in retaining a nomenclature which only 
perpetuates errors and cannot be made to express the true relations 
of the component parts of the Cretaceous System. They are quite 
right: it has perpetuated the error that the Gault as a whole is older 
than the Upper Greensand as a whole, and has prevented us from 
recognising long ago that they were to a large extent merely 
different lithological facies of one formation. 
There can be no question that the distribution of species affords 
a better basis of grouping than the lithological characters of deposits. 
Put in this way it seems a truism, but it is nevertheless a fact that 
our existing system of nomenclature ignores this principle, and does 
actually separate deposits which ought to be grouped together ; 
while it suggests a connection between ‘Lower’ and ‘ Upper’ 
Greensand which has no existence in reality. 
The French method of nomenclature is free from this reproach, 
and it has been preferred to our own by most other European 
nations. The French completely ignore lithological differences, and 
their subdivisions or stages include all deposits which yield a similar 
assemblage of fossils. 
D’Orbigny says that his principal object in undertaking the 
“ Paléontologie Frangaise” was the application of palaeontology to 
the natural classification of the formations, and it is to him 
that the French owe their nomenclature of the Jurassic and 
Cretaceous systems. He found that of the Cretaceous system in 
dire confusion, but when he had examined 593 species of Cretaceous 
Cephalopoda and Gasteropoda he felt himself justified in dividing 
the whole system into five distinct stages, each containing a special 
fauna. This was in 1843, and, abandoning the lithological names 
which were then current in France, he proposed new names for his 
stages, taken from those of towns or districts where each stage was 
well developed and specially fossiliferous. These five stages were 
Senonian, Turonian, Albian, Aptian and Néocomian. In 1852 
he added a sixth, having recognised that the group which he called 
Turonian in 1843, really comprised two stages with essentially differ- 
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