336 ROLLIN T. CHAMBERLIN 



rocks which are generally metamorphosed. In the basin of Laval 

 (Mayenne) the Stephanian Coal Measures with a conglomeratic 

 base lie unconformably upon overfolded Westphalian beds.^ 



Contemporaneously there occurred several belts of disturb- 

 ance in England somewhat apart from the main range. Here are 

 included the Lancastrian flexures and the folding of the Pennine 

 range, sometimes called the backbone of England. The folding 

 is pre-Permian and appears to have come rather late in the Car- 

 boniferous period. From the immense amount of rock material 

 which must have been removed from the broad arch of the Lake 

 District before the Permian sandstones were laid upon it, Jukes- 

 Browne suggests that this erosion possibly occupied the whole of 

 Stephanian time, thus making this folding of the same date as the 

 Armorican flexures.^ 



The Malvern and Abberley Hills are but the worn-down rem- 

 nants of a mountain chain which was formed in the Kmited interval 

 between the deposition of the Lower and Upper Coal Measures. ^ 

 According to Groom, this folding and faulting was essentially con- 

 temporaneous with that of the Hercynian system. This would 

 seem to be so if the Upper Coal Measures of Britain are equivalent 

 to the Stephanian, as they are given by Geikie.'' But according 

 to Jukes-Browne, the Stephanian is absent from England and the 

 Hercynian disturbance came after the English Upper Coal Meas- 

 ures.^ If this be the correct correlation, the formation of the Mal- 

 vern and Abberley Hills would seem to have been accomplished 

 slightly earlier than that of the main Hercynian system. 



On the border Hne between Italy and Austria the Carnic Alps 

 result from east-and-west plications which are referred to Carbo- 

 niferous times, but the precise stage remains doubtful. The prin- 

 cipal Paleozoic movements in the exterior chains of the western 

 Alps as well as in the eastern Alps are referred to this period with 

 similar qualification.^ 



' A. J. Jukes-Browne, op. cit., p. iS8. ^ Ibid., pp. 189-92. 



3 T. T. Groom, "On the Geological Structure of Portions of the Malvern and 

 Abberley Hills," Quart. Jour. Geol. Soc, LVI (1900), 176-95. 



4 Sir Archibald Geikie, Textbook of Geology, II (1903), 105 1. 



s A. J. Jukes-Browne, op. cit., p. 171. ^ Emile Haug, op. cit., pp. 830-31 



