329 The Oligocexe OF THE Southern United States 19 



Bolderian system. 

 Upper Rupelian system. 

 Lower " " 



Upper Tongrian " 

 Lower " " 



Tongrian. The name Tongrian was derived from the ancient 

 Flemish town of Tongres,* not far from Liege in eastern Belgium, 

 where typical lower Oligocene beds occur. 



Rupelian. The name Rupelian was derived from the river 

 Rupel, a tributary of the Escaut, since typical middle Oligocene 

 exposures are found along the valle)^ as at Boom. 



The Bolderian a Miocene horizon. Danaf refers the Bolderian 

 to the upper Oligocene, which it was thought to be by Belgian 

 geologists until 1884. In that year M. Van den Broeck:|; showed 

 that the Bolderian contains a typical Miocene fauna and should 

 be properly placed in the lower Miocene. He attributes the error 

 customarily made in regard to its geological position to the fact 

 that, in some localities, Oligocene fossils have been washed into 

 the Bolderian beds. 



The classification of the Oligocene proposed by M. Van den 

 Broeckll in 1894, was adopted by the Belgian government in 1896. 



* The town itself is named from the Tongri who originally dwelt in the 

 neighborhood. This tribe, under the leadership of the brave Ambiorix, re- 

 sisted the Roman army with such determined courage that Cjesar himself 

 was compelled to come from England to support his generals, and only by 

 a war of extermination were the Tongri subdued. The Romans were obliged, 

 by the continuance of this warfare, to remain several years in camp at 

 Tongres. During this time an extensive wall and fortifications were built, 

 the ruins of which are now the delight of archeologists. Pliny, who accom- 

 panied the army as historian, devoted himself to a study of the geology of 

 the region. He described, in particular, a remarkable carbonated spring. 

 This is generally identified with a large spring near the town called the 

 Fountain of Pliny. 



t Manual of Geology, 1894, p. 926. 



X Note sur la decouverte des fossiles miocenes dans les depots de I'^tage 

 bolderien a Wtenrode. Ann. Soc. R. Malac. Belgiquc, t. 19, 1S84. See also 

 by the same author. Rapport sur une excursion faite le 16 juillet 1874 au 

 Bolderberg, pres de Heosselt, Ann. de la Soc. Malacologique de Belgiquc, 

 IX, 1874. 



II Coup-d'oeil Synthetic sur 1 Oligocene Beige. Bruxelles, 1894. 



