496 A. J. Jukes- Browne — The Cenomanian Overlap. 



no representative of the former existed on the coast of Normandy nor 

 in the departments of Orne or Sarthe. We now know that there is 

 no such discordance, only an overlap, and that the Albian (both as 

 Gault and Gaize) occurs in Normandy as well as in the Orne. 



It is therefore satisfactory to find that some French geologists 

 are beginning to see that the Cenomanian transgression was only 

 part of a general Cretaceous transgression, which was due to a great 

 and continued subsidence, and not to a specially extensive subsidence 

 at the beginning of Cenomanian time. M. de Grossouvre, in a paper 

 read at the meeting of the French Association for the Advancement 

 of Science in 1901, has protested against the accepted view of the 

 ' Cenomanian transgression,' and his remarks are so decisive that 

 they deserve a larger audience than that to which they were specially 

 addressed. From them I quote the following translated paragraphs : — 



" To begin with, it is essential to point out that this transgression 

 was not a sudden and almost instantaneous phenomenon, and that 

 on this account it cannot be considered as a disturbance of a definite 

 date furnishing everywhere a clearly-marked point of departure. 



" Let us examine, for example, what happened in the northern 

 and central parts of Europe. We know that large areas were raised 

 into land toward the close of Jurassic time ; then with the opening 

 of the Lower Cretaceous era we perceive the sea advancing from 

 the Mediterranean region to invade by degrees the territories 

 which it had temporarily abandoned. In one place it is the 

 Spatangus limestones (Neocomian) which rest on the Jurassic; in 

 another it is the sands with Am. Milleti, or the clays of the zone 

 of Am. mammillaris ; elsewhere it is the zone of Am. inflatus which 

 commences the transgressive series. 



" This slow and continued progress of the invasion of the 

 continental area by the sea is observable not only in northern and 

 central Europe, but can be traced in nearly every part of the globe. 

 . . . [References are here given to the transgression in North 

 America, Brazil, and West Africa.] 



" I content myself with these few examples, which it would be 

 easy to multiply, and from the above statements I think I may 

 safely draw the conclusion, that the Cenomanian transgression 

 represents only one phase or episode in a long period of slow and 

 continued transmutation, which can be followed from the very dawn 

 of the Cretaceous era. Moreover, the movement did not stop with 

 the Cenomanian epoch, and I could show that it was continued up 

 to the end of Campanian time (Upper Senonian). 



" It has been said that at the epoch of the Am. inflatus beds it 

 was so pronounced that it constitutes by this very circumstance an 

 exact chronological datum which can everywhere be recognized. 

 This in my opinion is another mistake, for if at many points the beds 

 with Am. inflatus are seen in transgression over the older deposits, 

 in many other places we can see the free Cenomanian resting directly 

 on the Jurassic and sometimes on the Primary rocks. Is it not so at 

 Mans, where D'Orbigny took the type of his stage ? In Aquitaine, 

 at Essen in Westphalia, in Bavaria, in Saxony, Bohemia, Galicia, 



