98 LIAS .OF ENGLAND AND WALES: 
Joints in the Carboniferous Limestone are infilled with various 
materials, for the superincumbent strata have tumbled or been 
washed into fissures, and we see the " broken beds " above, as in 
the case of Purbeck Beds where they overlie fissures in the 
Portland rocks. 
Veins of Liassic material in the Carboniferous Limestone, have 
been noticed by Moore in several localities on the Mendip 
Hills, in the Bristol area, and in South Wales. Some of the 
veins traverse the rock in a direction east and west, and they are 
intersected by others from north to south. The veins are 
from a few inches to 6 feet wide, and they are accompanied by 
Heavy Spar, Galena, and Blende. The most remarkable dis- 
covery was made at the Charter House Lead Mine, south of 
Blagdon, where at a depth of 270 feet from the surface, a 
number of fossils were obtained, including Land-shells of the 
genera Valvata, Vertigo, Proserpina, and Helix, and over 50 
species of Brachiopoda and Mollusca; as well as Foraminifera, 
Fish-remains, &c.* 
The age of many species is doubtful, for Moore subsequently 
obtained Planorbis mendipensis, Involutina liassica, and other 
forms in the lead-mining districts of the North of England ; t 
while the abundant remains of Acrodus and Hybodus are 
suggestive of lihsetic accumulations. It must be remembered 
that the remains of Microlestes, found in a fissure near Frome, 
occurred in association with in-fillings of Oolitic as well as 
Carboniferous age.J 
With regard to these veins, Moore was of opinion that " In 
general they are of Liassic age; but the mineralogical and 
palaeontological variety they present, show that they were not 
formed contemporaneously. Probably they were for a long time 
open to the Liassic seas, and must in many instances have received 
their contents very gradually ; a Liassic fauna not only inhabited 
the ocean above, but lived within the Carboniferous Limestone 
walls of the open fissures,, and the remains of Gasteropoda and other 
organisms may still be seen attached thereto."|| It is possible, 
that there were open fissures on the sea-coast in Liassic times, as 
we see at the present day in the Carboniferous Limestone near 
Button in South Wales, but the admixture of fossily suggests that 
in-fillings may have taken place at various periods, in some cases 
perhaps subsequent to the Jurassic epoch. In some of their 
features, these Liassic veins resemble the chasms and * pipes ' in 
the Kentish Rag of Maidstone, where in-fillings of fossiliferous 
brickearth occur. 
* Quart. Journ. Geol. Soc., vol. xxiii. pp. 454, 481-495 ; vol. xxxvii. pp. 67, &c. ; 
Rep. Brit. Assoc. for 1864, Sections, p. 59 ; Geol. Mag., 1864, p. 235. 
fRep. Brit. Assoc. for 1869. p. 369. 
$ Owen, Quart. Journ. Geol. Soc., vol. xvi. p. 492. 
|| Quart. Journ. Geol. Soc., vol. xiiii. pp. 455, 488. 
See Foster and Topley, Ibid., vol. xxi. p. 454 ; and TopleyJGeol. Weald (Geol. 
Survey), p. 179. 
