478 Corre.^pondcnce — Dr. A. Irving. 



underneatli the sea to the neighbourhood of Nevin, it would occupy 

 the position assigned to the parent fault by the discussion of the 

 earthquake phenomena. 



The principal shock was preceded by an earth-sound, and followed 

 by at least five shocks, originating apparently at the north-western 

 extremity of the principal focus. In addition, six slight shocks and 

 two earth-sounds were recorded by single observers ; and, if these 

 be included in the earthquake series, it follows that seismic action 

 was gradually withdrawn from the extremities of the focus and 

 ultimately confined to its central region. 



COK,I^ES:P01T3D.E3^CE. 



THE KEUPER BASEMEXT BEDS. 

 Sir, — My recent paper in the Geol. Mag. (April, 1904) on the 

 Keuper of Devon recalls the difficulty of tracing horizons in those 

 beds, which I have found in common with other workers in the 

 field in former years. An illustration of this came before me when 

 the British Association met at Bath in 1888. An excursion into 

 the country some miles from Bath had been planned, and was 

 carried out under the conduct of a well-known local ' geologist.' 

 The sections that came under our observation included those of 

 a rather deep cutting on a railway, which, as I understood, had not 

 been long constructed. These sections were very fresh and of quite 

 a mural character, the bare rock being exposed almost everywhere. 

 Yet a strange error of observation was made by almost all the 

 company present; all, I believe, except Professor Boyd Dawkins 

 and myself. The attention of some forty or fifty people — not all 

 amateurs, by any means — was called hy the director to some irregu- 

 larities of bedding in the massive Keuper sandstones, as indicating 

 the line of unconformity between them and the Old Eed Sandstone, 

 by that overlap, which we know to be of frequent occurrence. It 

 was nothing of the sort ; for after most of the company had been 

 hurried on, on account of the trains. Professor Boyd Dawkins and 

 I made a careful observation of the true line of unconformity near 

 the level of the railway-line. There the Keuper sandstones were 

 seen lying horizontally upon the planed-off, upturned edges of Old 

 Eed sandstones and shales, furnishing as typical a case of normal 

 unconformity as one could wish to see. A.. Irving. 



:]VCXSCJEI1jXj JLIiTEOTJS - 



Museum of Practical Geology. — We are glad to hear that the 

 Museum of Practical Geology will not be closed in future during 

 cleaning. So many people from the country are up in town this 

 time of year that we are surprised that such a sensible concession 

 has been so long delayed. The Museum in future will be open 

 all the year round. 



