232 



THE GEOLOGIST. 



its own ink— an honour which this predaceous mollusk could never 

 have contemplated. 



The quarry at Dumbleton, a little further round the hill to the east, 

 affords a similar section ; but, if anything, the fossil-insect-bed is 

 thicker there. As our remarks in this article refer solely to the geology 

 of Gloucestershire, it would be out of place to say much about similar 

 deposits elsewhere; but we may just observe that this limestone, with 

 the like fossils, has been traced in other counties, especially in Somerset- 

 shire, where it has yielded to the energetic researches of Mr. C. Moore, 

 ofBath, a rich harvest of organic remains. It may be noticed also at 

 Gretton, where a fine specimen of a large fish, a species of Pachj^cormus,^' 

 was not long since procured ; and we have detected it, though much 

 reduced in thickness, being scarcely an inch thick, at Churchdown Hill, 

 one of the outliers before alluded to between Gloucester and Chelten- 

 ham. In all probability, therefore, it will be discovered wherever the 

 upper Lias itself is present, and the extension of so thin a calcareous 

 band, characterized by nearly similar fossils, over a very considerable 

 area, is a fact or thy of attention. The collector may search over a 

 good deal of this limestone without success, and yet he must never 

 despair, for, when we discovered the fine dragon-fly above-mentioned, 

 it so happened that a geological friend had broken up a large block all 

 but a small fragment, and in this the nearly perfect ^shna was lying, 

 with its expanded wings spread out in their natural position of flight, 

 or as if laid out with all the skill and care of an accomplished 

 entomologist. 



We must now proceed to give some account of the Marlstone on 

 which the upper Lias rests in this county. The upper portion consists 

 of a rough, very hard stone, of a blue colour internally and of a brown 

 colour externally ; the lower part is more sandy, with masses of sand- 

 stone and iron-nodules. It is to obtain this rock that the upper Lias 

 clay is quarried, as it forms a useful stone for walls and roads, although, 

 owing to the introduction of the mountain-limestone from Bristol, it is 

 not so often employed as it used to be. It presents a very diff'erent 

 lithological aspect to the muddy deposits above and below it j and, from 

 its indestructible nature, it forms a very good geological horizon in this 

 and most other districts where it prevails. It abounds in marine shells, 



* Many species of this curious geuus have been met with at Whitby, and in 

 the upper Lias at Ilmiustcr. E.P.B. 



