Correspondence — Rev. Dr. Irring. 333 



the authors believe to be Carboniferous and to yield possible indica- 

 tions of coal, reaching to near Assouan, where it meets the granite 

 and basalt of that region ; a few miles south the sandstone begins 

 again and continues to Wadj' Haifa, broken only by granite dykes. 



The granite is intrusive into and alters the sandstone, whilst the 

 latter reposes upon the basalt, and in some cases was deposited 

 against upstanding basaltic masses. Unmistakable lavas occur near 

 the Nile E. of Minieh and W. of Assiout. 



A description of some remarkable faults is given, and A^arious 

 minerals are noticed as occurring in the sedimentary rocks and the 

 bed of an ancient river. 



coK,E,:n]si='OisriDEijq"OE. 



PERMIAN IN DEVONSHIRE. 



Sir, — After a careful perusal of the article on this subject in this 

 month's Number of the present volume (pages 247-250) by Mr. 

 W. A. E. Ussher, I am rather at a loss to see the actual drift of it. 

 The author shows he is acquainted with several foreign geologists ; 

 and that he has seen the German Eothliegendes ; he quotes opinions 

 of one or two foreigners (notably Herr von Reinach) which cor- 

 roborate my assignment in 1888 of the breccia-series of Devon to 

 the age of the Eothliegendes (pp. 247, 248) ; and a little further 

 down (p. 248) he puts forward a " probable correlation " of the 

 Devon series of Teignmouth and Dawlish with rocks of the Nahe 

 district, which agrees in all essential matters with the parallelism 

 drawn in my papers (in the Q.J.G.S. of 1888 and 1892) between 

 the Devon breccia- series and the Rothliegends of the Thiiringen 

 country, and of the country further east in Central Germany, 

 particularly in the Gera district, — a parallelism based on previous 

 first-hand knowledge of the German series. I commend these 

 regions with that around the Hartz to any one who wishes to 

 know the German Eothliegendes. 



While, then, I entirely agree with Mr. Ussher that "no correlation 

 framed on a partial or even intimate acquaintance with the South 

 Devon coast-section only can be regarded as conclusive," I must ask 

 you to allow me to remind readers of the Geol. Mag. of the two 

 papers published by me in the year 1884, (1) "On the Dyas and 

 Trias of Central Europe" (Q.J.G.S.), (2) "On the Permian-Trias 

 Question" (Geol. Mag.): papers, of the existence of which Mr. 

 Ussher could not have been ignorant at the time he penned the 

 paragraph which opens with the above-quoted remark (pp. 248, 249), 

 and of the value of which M. Jules Marcou expressed his strongest 

 appreciation to me at the time. 



The information given on p. 248 respecting the contemporaneous 

 igneous rocks of the Nahe country adds little or nothing to our 

 previous knowledge of them, since we read in Credner's ' Geologie ' 

 (6th edition, 1887), "The two lower groups [of the Eothliegendes 

 of the Saar-Rheingebiet] are grouped by E. Weiss as Carboniferous 

 Eothliegendes, described by von Dechen as Carboniferous rocks poor 



