GAVEY — LOWER LIAS, GLOUCESTERSHIRE. 31 



species of Os^rea with both valves preserved, but generally in a crushed 

 state ; there were also a considerable number of Belemnites (B. ovalis 

 and another species) . Many of them were much corroded, as though 

 they had been lying for some time at the bottom of the sea ; whilst 

 others showed every appearance of having been buried alive in the 

 deposit. 



Layers and rounded concretions of ironstone were found at various 

 depths, but not in continuous beds ; they were also of different thick- 

 nesses — from two to twelve inches, and from one to a few feet in length 

 and width. Their surface was generally covered with very interest- 

 ing and well-preserved fossils. The stone has not been assayed, but 

 is supposed to contain a large per-centage of iron ; it is very hard, 

 with a conchoidal fracture. The colour is a light brown when exca- 

 vated, but on exposure the stone oxidizes to a dark brownish red*. 



In the shale I found numerous spherical nodules of an impure lime- 

 stone or indurated shale, varying from one to eight or nine inches in 

 length, with the outer surface soft, but becoming very hard towards 

 the centre. When broken open they disclosed a hard black sub- 

 stance ; this, upon examination, was found to have been a crustacean, 

 which had formed the nucleus ; the extremities of the animal were 

 not unfrequently well preserved in the exterior and softer part 

 of the stone, but not so the body, for, so rarely is the true form of 

 the crustacean distinguished in these nodules, that out of several 

 hundreds that I have broken I have met with but four or five spe- 

 cimens in which the outline of the body can be fairly traced. These 

 nodules do not affect a regular stratification, but lie promiscuously 

 throughout the shale, and resemble in colour and hardness those of 

 the London Clay. 



There are other nodules in the shale, but they are comparatively 

 rare and have more the appearance of Coprolites. These are not so 

 hard, and do not, as far as I ascertained, enclose any fossil remains. 



Only a few detached bones of Saurians have been found ; viz. a 

 spinous process and a few vertebrse of the Plesiosaurus. 



No beds of limestone were met with, and the shale was generally 

 of the same description throughout, somewhat arenaceous and occa- 

 sionally laminated ; it became much harder and heavier on sinking 

 through it to a depth of 90 feet, which would be 164 feet from the 

 surface at the highest point. The beds are nearly horizontal, dip- 

 ping slightly to the north, at an angle of one degree ; they do not 

 seem to have been much disturbed, although the shale is much dis- 

 integrated f. 



In the open cutting at the north end of the Tunnel, beneath the 

 loamy clay and gravel that forms the surface-diift, a small deposit of 



* Much ironstone occurs in the top beds of the Lower Lias in several other 

 parts of Gloucestershire. It was formerly worked at Robinswood-HiU near Glou- 

 cester, and contains a large per-centage of metal. The beds at Mickleton are 

 particularly rich. [Note by the Rev. P. B. Brodie.] 



f It reqiured to be expeditiously worked, for otherwise, if left and exposed to 

 the air for three or four days, the superincumbent earth being supported only by 

 timber preparatory to the brickwork being put in, the shale would begin to swell 

 and break the timber, thereby endangering the work. 



