328 M. F. i. CORNET ON THE UPPER CRETACEOTJS SERIES 



on the opposite slope of the great valley, that is to say under the 

 town of Mens and northward, the Landenian system is separated 

 from the Cretaceous series by a very considerable thickness of highly 

 fossiliferous marine calcareous freestone, known by the name of 

 Calcaire grossier de Mons, and by marls and freshwater lime- 

 stone with Physa^ belonging to the Tertiary series. These deposits 

 constitute the stage to which Belgian geologists have given the name 

 of the Montian system (Systeme Montien). See fig. 1, N'o. 4. 



C to E. Cretaceous Series. 



C. Tufaceous CJialk of Cijoly. — This is a calcareous rock of coarse 

 texture, somewhat friable, white or slightly yellowish, chiefly 

 composed of carbonate of lime. It forms thin beds regularly 

 stratified, in which are occasionally found nodules of grey flint. 



The Tufaceous Chalk of Ciply is the geological equivalent of a 

 part of the Tufaceous beds of Maestricht. The following are some 

 of its characteristic fossils : — 



Ostrea vesicularis, Lamh. 



lateralis, 'NiU. 



Janira quadricostata, d'Orh. 

 Crania Davidsoni, Bosq. 



comosa, Bosq. 



nodulosa, Honigh. 



Thecidea papillata, Bronn. 



longirostra, Bosq. 



recurvirostra, Defrance. 



Argiope Davidsoni, Bosq. 

 Terebratulina striata, Wahl. 

 Pentagonaster quinquelobus, d^Orh. 

 Hemipneustes striato-radiatus, d^Orb. 

 Cassidulus elongatus, Agass. 

 Oatopygiis pyriformis, Agass. 

 Temnocidaris danica, Cotteau. 

 Porosphora nuciformis. Gold/., sp. 

 Trochosmilia Faujasi, Edw. ^ H. 



"With these species are found numerous Polyzoa. At many places 

 in quite the lower part of these beds a conglomerate occurs, its 

 thickness varying from some inches to several feet. It is formed of 

 brown nodules, re-united by a more or less coherent paste of car- 

 bonate of lime. The greater number of the nodules have a diameter 

 from -jig- in. to 2 inches. Their chemical composition, determined by 

 M. Peterman, director of the Agricultural Station of Gembloux, is 

 as follows * : — 



Lime 51-22 



Magnesia 1'30 



Oxide of Iron and Alumina 2'56 



Potash 0-21 



Soda 0-53 



Carbonic acid 18'61 



Sulphuric acid 1*36 



Phosphoric acid 22*48 



Silicic acid 1'14 



Isoluble matter in the oxides 0*22 



Organic mater. Traces of Fluorine and "1 q.ow 



Chlorine j 



100-00 

 This conglomerate is that to which the name of " Poudingue de 



* Bulletin de rAcademie Royale de Belgique, 2^ ser. vol. xxxix. 



