Correspondence — Alex. Somervai! — J. Smith. 28S- 



a number of vents made their appearance and discharged a succession 

 of fragmental materials, which differ from the yellow tuff in showing, 

 both macroscopically and microscopically a greater variety of com- 

 position, and in the proofs which they furnish of a succession of 

 eruptions both in space and time and a gradual southward shifting 

 and diminution of the vigour of the eruptive energy. The largest 

 and most ancient of the volcanoes of this latest period is that of 

 Agnano, the crater of which is built up of layers of pumice, ashes, 

 lapilli, soft grey tuff, and beds of scoriae. Not improbably it was 

 from this eruptive centre that the trachy-andesitic lava of Caprara 

 issued. Other volcanoes of the same series are Astroni, Solfatara, 

 the two small vents of Cigliano and Campana behind the north- 

 western slopes of Astroni, the last-named example showing three 

 concentric rings, within the innermost of which a beautifully perfect 

 little crater marks the last efforts of this vent. The crater-lake of 

 Avernus belongs likewise to the latest group, and perhaps it was 

 the water percolating from this basin to the thermal springs of 

 Tripergole which, in September, 1538, gave rise to the explosion 

 that built up Monte Nuovo, the youngest of the cones of the 

 Phlegrsean Fields. 



ooiaiaE!s:E'on:>T-nD.BisroE. 



THE BASE OF THE KEUPEE, IN SOUTH DEVON. 



Sir, — In replying to Dr. Irving's article in your April number, 

 I must preface the same by regretting my use of the term 

 "dolomitic" which somahow crept in; but which, I think, hardly 

 amounts to a " caricature " of his description. I would further add 

 that I never doubted the existence of the fault at the Chit rock. 



On the main issue I still hold that the Otterton Breccias are not 

 again brought up on the east side of the river Sid; and that the 

 beds here described as such, occupy a much higher horizon, being 

 separated from the former by a considerable thickness of red sand- 

 stones. On this point, however, I am willing to wait — with an open 

 mind — the results of other observers who may choose to devote 

 their attention to this matter. Alex. Sohekvail. 



ToBQTJAY N.H. Society. 

 16th April, 1904. 



MAEINE FOSSILS IN UPPER COAL-MEASUEES. 

 Sir, — On the 23rd April I found in the Craigmark Burn, 

 Dalmellington, Ayrshire, some marine shells in the Upper Coal- 

 measures. They occur in a cliff on the right bank of the stream, 

 about half a mile up from the village of Craigmark. The cliff is 

 about 30 feet high, its upper part composed of dark shale, and its 

 lower part of lightei'- coloured shale with nodules and bands of 

 ' curly ' ironstone. About the middle of the cliff there is a 9 inch 

 band of bituminous shale with fish-remains, and in the centre of 

 it the marine band occurs. 



