ITS PROF. T. T. GROOM ON THE GEOLOGICAL [Feb. I9OO, 



In Southern Scotland unconformity between the Upper Coal 

 Measures with Spirorbis and the older Measures has been observed in 

 the coalfields of Ayr, Dalmellingtou, and Sorn 1 ; and in the Sanquhar 

 Coalfield, where the Upper Coal Measures rest on faulted older 

 Measures. 2 Unconformity between the same beds has also been in- 

 ferred in Lanarkshire 3 and elsewhere. 4 



In the remaining British coalfields, so far as I am aware, no un- 

 conformity has been detected hitherto between the Upper and older 

 Coal Measures and in certain districts where undoubted Upper Coal 

 Measures are present, as, for example, in the Warwickshire Coalfield, 

 the unconformity, if present at all, is apparently but slight. 5 



In the coalfields of Southern England and Wales the Coal Measures 

 have been divided into an Upper, Middle, and Lower series ; but, as 

 Mr. Jukes-Browne points out, there is reason to doubt whether the 

 Upper Series corresponds with the true Upper Coal Measures of Central 

 and Northern Britain ; and Mr. Strahan 7 has recently expressed his 

 conviction that the true Upper Coal Measures are absent from the 

 South Wales Coalfield. But in Devon Mr. Somervail has recognized 

 above the true Culm Series a group of conglomeratic beds which are 

 apparently older than the Permian, and rest unconformably upon 

 the Culm. s Further research may show that these conglomerates 

 correspond with the Upper Coal Measures of other parts of Britain. 



Sufficient evidence has now been adduced to show that the uncon- 

 formity at the base of the Upper Coal Measures in the Abberley 

 district is not merely a local phenomenon, and that considerable 

 disturbance took place in Britain in Coal-Measure times. Similar 

 but more convincing evidence of extensive movements during this 

 period on the Continent has long been known. This is admirably 

 brought out by Suess, who recognizes in Western and Central 

 Europe several important old mountain-ranges: the Armorican, 

 extending from Southern Ireland to the Central Plateau of 

 France; the Yariscian, running from the northern edge of the 

 Carpathians to the same plateau; and the Iberian, extending 

 from Gralicia and Northern Portugal to the Guadalquivir in 

 Southern Spain. These ranges all arose towards the close of 

 the Carboniferous period, 9 and have been collectively termed 

 the Hercynian System, a name due to Marcel Bertrand. 10 

 The Hercynian folding has affected all rocks ranging up to, and 

 including portions of, the Coal Measures. The denuded and folded 

 series is overlain by the Permian, and in places by the Upper Coal 

 Measures. The Hercynian ranges have been subjected to later 



1 Mem. Geol. Surv. Scotl. 1869, Expl. Sheet 14, pp. 19 & 22. 



- Ibid. 1871, Expl. Sheet 15, p. 33. 3 Ibid. 1873, Expl. Sheet 23, p. 35. 



4 Ibid. 1872, Expl. Sheet 22, p. 22, & ibid. 1879, Expl. Sheet 31, p. 32. 



5 H. H. Howell, 'Geol. of Warwickshire Coalfield' Mem. Geol. Surv. 1859. 

 G ' Building of the British Isles ' 2nd ed. (1892) p. 157. 



■ Rep. Brit. Assoc. 1898 (Bristol) p. 865. s Ibid. p. 877. 



9 ' Antiitz der Erde ' vol. ii (1888) pp. 104, 111, 114, 117, 124. 129, 130, 150 

 et seqq., 165. 

 10 Bull. Soc. geol. France, ser. 3, vol. xv (1887) p. 438. 



