46 • Observations on the 



especially rtiadrepore coral, chlorite, and zeolite. This circum- 

 stance strongly impresses in my belief its igneous origin, and 

 elevation by a vis ab infra, as well as its external appearance, 

 and form of ciystallization, I found in the trap some spe- 

 cimens of agate, and some singular instances of the con- 

 version of trap with coralline perforations into limestone. Some 

 will suspect a fallacy in this, but I am convinced of its possi- 

 bility by various examples. Of such conversions by a natural 

 process, we have instances in fossils, for we find shells always 

 primarily constituted of calcareous and animal matter, trans- 

 muted into the composition of the strata in which they exist. 



In the sandstone of the vale of Berkeley we find shells. I 

 have specimens from the formations here of a peculiar rock at 

 "Woodford near Berkeley, two varieties of alabaster, pentacri- 

 nite, saxified wood, and amygdaloid. 



Through these vales of Berkeley and Gloucester, the mighty 

 vassal of the Bristol channel, receiving half its tide, the Severn, 

 carries its waters : and this same river which, by ocular 

 deception at WindclifF, seems to menace Wales on one side, 

 and Gloucestershire on the other, gave rise, at a comparatively 

 recent period, to a deluge of no ordinary local importance. 

 There is a traditional relation of it among the aboriginal inha- 

 bitants, who call it the " Great flood." It occurred in 1607, 

 accordino- to an account in the Gentleman's Magazine for 1762, 

 and reached the summit of very considerable eminences upon 

 its banks. 



At Abston and Wick, near Bristol, Bigland, in his History of 

 Gloucestershire, gives us the following fossil collections : coal, 

 belemnites, astroites, serpent stones, duck's bills. Sir Robert 

 Atkins mentions a cavity under ground, having several funnels, 

 all stopped up. At AustclifF, banks of the Severn, Bigland 

 talks of " a considerable quantity of alabaster under and near 

 the clifF, thrown up by the tide. Tliat this cliff formerly ex- 

 tended further is evident. Out of the cliff have been taken the 

 grinding teeth of some animal, supposed to be those of an ele- 

 phant. They were nearly as large as a man's fist, and their 

 colour, by lying so long in the ground, was black." At Aure, 



