Mr Lyell on the Loamy Deposit of the Rhine. 115 



from Andemach to May en) is from 15 to 30 feet. In one place 

 the loess is clearly exposed, resting upon volcanic matter, and at 

 the junction it alternates with it. Small portions of pure loess 

 are there entangled in black volcanic matter. In many other 

 sections, the same loess is seen covered with beds of pumice, 

 trassy pumiceous sand, and small dark volcanic cinders, forming 

 upon the whole a mass from 10 to 15 feet in thickness, and 

 very like that which covers Pompeii. There is, in this instance, 

 no loess intermixed, nor any alternation at the point of junction, 

 as might have been expected, if the volcanic matter had been 

 washed over the loess by running water. At one place in the 

 Kirch weg I observed, in a perpendicular section, an aggregate 

 of small fragments of pumice resting on loess. The latter had 

 wasted away, so that the incumbent mass of pumice was under- 

 mined and overhanging. It thus exhibited its under surface, 

 projecting several feet from the face of the precipice, and it ap- 

 peared flat and even like the ceiling of a room, shewing that 

 tliere was an abrupt passage from loess to the pumice. It may 

 also be seen, on comparing several sections, that before this 

 shower of pumice fell, the loess already formed the slope of a 

 hill descending towards the valley of the Rhine, just as it does 

 now where no volcanic superstratum has been spread over it. I 

 conceive, therefore, that the valley of the Rhine had assumed its 

 actual shape, and that the loess had been considerably denuded, 

 before the occurrence of the eruption which produced the great 

 bed of pumice near Andemach. 



I think it unnecessary to give more details respecting the sec- 

 lions near Andemach, because some of them have been faith- 

 fully described by Mr Steininger, Dr Hibbert *, and others ; and 

 these geologists have declared their conviction that some of the 

 volcanic eruptions were contemporaneous with, and others sub- 

 , sequent to, the deposition of the loess. 



On descending the hill to the village of Plaidt, on the road 

 from Ochtendung, at the distance of about four miles from 

 Andernach, I saw loam resembling loess covered with eight 

 feet of volcanic matter, consisting of stratified beds of pumice, 

 dark volcanic sand, lapilli, &c. I found no shells in this loam. 

 " See Hibbert's extinct Volcanoes of Neuwied, p. 221. 



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