340 STKATIGRAPHICAL GEOLOGY 



and in the Permian of Thuringia. Mr. Watson suggests that they 

 may have been made by Gordonia. 



D. CONTINENTAL PERMIAN STRATA 

 1. France 



Small tracts of Permian rocks occur at many places round the 

 great Central Plateau of France (see map, Fig. 102), most of them 

 abutting against the ancient rocks of this plateau, and passing out- 

 ward beneath the newer deposits which surround it. They appear 

 to belong to two separate areas of deposition, the one group on the 

 north extending from a point south of Berry by Buxiere and 

 Moulins, and reappearing on the Morvan near Autun where there 

 are two basins or troughs. The other area lay to the south and 

 south-west of the plateau, patches of its deposits occurring near 

 Brive, near Rodez in Aveyron, near Carmaux in the Tarn, and 

 again from Broquies in a long strip to Grassessies on the Montagne 

 Noire. 



The beds of the Autun basin form the type of the Autunian 

 stage. They overlie the Stephanian measures, and the lowest set 

 of beds which are classed as Autunian are really passage-beds, con- 

 taining a flora like that of the beds below, except that it includes 

 Walchia piniformis and Callipteris conferta. These beds are about 

 1300 feet thick and are entirely of freshwater origin, consisting of 

 sandstones and bituminous shales, with beds of magnesian lime- 

 stone full of Cyprids ; and they form the zone of Igornay. 



They are succeeded by another group of similar rocks (zone of 

 Muse) with two valuable beds of oil-shale, and a more typical 

 Permian flora. Lastly there is an upper stage (zone of Millery) 

 about 1500 feet thick, consisting of shales and thin coal-seams, 

 one of the latter being the famous Boghead coal. The whole 

 series is about 4000 feet. 



This Autunian Series has yielded a rich harvest of vertebrate 

 remains ; the Amphibia have been described by Gaudry, and 

 include Protriton petrolei, Pleuroneura Pellati, Actinodon Froissardi, 

 and Stereorachis dominans. Fish are numerous, and silicified stems 

 of tree-ferns (Psaronius) are common in the upper beds. 



At Bourbon and Buxiere the series is not so thick, and consists 

 more largely of felspaihic sandstones derived from the erosion of 

 the neighbouring granitic and gneissic rocks. The lowest beds, 

 however, include bands of oil -shale and black limestone, and 

 doubtless belong to the Autunian lake-basin. 



Wherever the summit of the Autunian is exposed, it is over- 



