524 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



Rouen, and Le Mans (1847-58). His support of D'Orbigny's 

 groups brought Hebert into conflict with his rival, the g'ifted 

 but rather fiery native of Provence, Henri Coquand. 



The south and south-west of France had been Coquand's 

 field of research, Hebert's work had lain in the north of France, 

 and the facies variations of the rocks were undoubtedly chiefly 

 answerable for the want of harmony in the results obtained 

 by the two field geologists. Coquand was engaged for eight 

 years on a survey of the Charente, but his results, published 

 1858-60, would neither agree with D'Archiac's nor with 

 D'Orbigny's systematic sub-division of the Cretaceous system. 

 Coquand found that the Cretaceous deposits in the south 

 began with the Upper Cenomanian, and that the most natural 

 sub-division would be into eight groups, which were mainly 

 characterised by the abundance of species of the Hippuritid 

 family, whereas in the north of France there were scarcely any 

 Hippuritids. 



Coquand erected a number of palaeontological zones for the 

 Cretaceous development in the Charente, and traced the 

 continuation of these into Provence and Algeria. To the 

 Cenomanian and Turonian, Coquand ascribed the stages. 

 Rhotomagien^ Gardonien, Carentonien (zone of Exogyra 

 colutnba), Angoumien, and Provencien; to the Senonian and 

 Danian he ascribed the stages Coniarien, Santonien, Campanien, 

 and Dordonien. In 1862 he added a new stage, Mornasien, 

 between the Carentonien and Angoumien for the sandstones of 

 Uchaux and Mornas; and in 1869 ne inserted a new stage, 

 Ligerien, between the Carentonien and Mornasien. Coquand 

 also added the stage Barremien to the lower Cretaceous 

 between Neocomien and Urgonien for Cephalopod-bearing 

 strata at Barreme and other localities in the Basses Alpes 

 which D'Orbigny had regarded as a facies of the Urgonien. 



Coquand's special nomenclature for the southern Creta- 

 ceous development was willingly accepted by the geologists in 

 the south of France, but was strongly contested by Hebert. 

 The Parisian stratigrapher also doubted the presence of true 

 equivalents of the White Chalk with Belemnitellas in the areas 

 of Touraine, Charente, Dordogne, and Provence ; in his 

 opinion, Coquand had erroneously compared the Dordonien 

 and Campanien with the Senonien and Danien of the north ; 

 Hebert thought they represented only the lower Senonien. 



At the present day the general tendency in France is to 



