THK OI.KKK'KNi: SKI; IKS 563 



ll.tmpshiiv Uisin, the general succession corresponds very cloeely 

 with that dt' our country. Belgian geologists have divided tin in 

 into two stages: (1) the Tongrian, from Tongres near Limbouii,', 

 ami (2) the Rupelian, from the river Rupt-1 south of Antwerp, on 

 which is situate the town of Boom. 



Tongrian. There is in most parts of Belgium a break 

 between the Tongrian and the Eocene Series, the Oligocene having 

 a layer of quartz-pebbles at the base which rests indifferently on 

 various iiu-iiilirrs of the lower series. 22 It is divisible into two 

 parts, a Lower and an Upper Tongrian. The Lower Tongrian 

 is of small thickness, from 20 to 60 feet only, and consists of fine 

 sands and sandy clays with Ostrea ventilabrum (= 0. prona, Wood), 

 Astarte Omaliusi, Cardium porolosum, Dosinia incrassata, Pecten 

 bellicostaius, Valuta decora, Clavella longceva, Cancellaria evulsa, 

 a marine fauna which closely resembles that of Brocklehurst 

 (Middle Headon). 



The Upper Tongrian is an estuarine or fluvio-marine group, 

 equivalent to the Bembridge Beds, and comprises three members, 

 as below, but the total thickness is only 20 to 30 feet. 



3. Sands of Vieux Jones with Potamides plicatus and P. elegans. 

 2. Green clays of Henis with Dosinia incrassata and Mya angustata. 

 1. Sands of Bauterem with Cyrena semisfriata, Cerithium LamarcJci, 

 Melania muricata, Bithinia helicella, and B. plicata. 



Rupelian. This is a purely marine formation, and appears to 

 be the equivalent of our Hanistead Beds. It commences with the 

 sands of Berg, characterised by the abundance of Pectimculus 

 obovatus, with Valuta Bathieri, Cominella Gossardi, Tritonium 

 flandricum, and locally it includes a band of clay with Nucula 

 compta. 



The Upper Rupelian consists of a thick mass of sandy clay, the 

 Argile de Boom, which contains many fossils, some of the more 

 important being Valuta Rathieri, Fusus elongatus, Triton flandricum, 

 Corbula pisum, and Leda deshayesiana ; it has also yielded many 

 remains of vertebrates, including two Sirenians (Halitherium), 

 several birds, turtles, and a number of fish, chiefly Elasmobranch 

 (Lamna, Odontaspix, Oxyrhina, Carcharodon). 



2. Germany 



Since the name Oligocene is based upon the deposits of this age 

 found in the north of Germany they really form the type of the 

 series, but although they occupy a large area in that country 

 they are to a great extent concealed beneath Miocene and newer 

 deposits. Here and there, however, the Oligocene Beds are 



