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Liassic fossils embedded in it has led to its bemg generally 
accepted as being of Liassic age. Although late in making the 
discovery, however, and at the risk of running counter to accepted 
theories, the writer would venture to doubt whether the Dyke is 
exclusively Liassic, for when examining it during the past 
autumn, in company with the Rev. H. H. Winwood and another 
friend, several vertical belts of hardened Red Marl were observed, 
which appeared to be relics of an earlier age. It is difficult 
to construct an exact section of the Dyke, but the accompanying 
illustration will be sufficient to explain the special feature now 
pointed out. It gives a typical cross section of the Dyke, as it 
stands up gaunt and bare from the Mountain Limestone which 
forms the floor of the quarry, and by which it is flanked on 
both sides. 
The north side of the Dyke is of a‘very decided Liassic 
appearance, but in the centre of the quarry, where it attains its 
greatest thickness, there is an included mass of Mountain Lime- 
stone, on the south side of which there occur the belts of Red 
Mar] alluded to, alternating with belts of a Liassic character. 
It is possible that, what the writer has described as Red Marl, 
may be the same that Mr. Moore has elsewhere referred to as 
Hematite, but in either case it appears to indicate that the 
infilling of this old Dyke belongs to at least two different periods, 
the one possibly of Keuper and the other of Liassic age. 
In connection with this suggestion it must not be forgotten, that 
the principal upheaval of the Mendip hills, and the formation of 
most of the fissures which have subsequently been filled up by 
more recent strata, occurred at the close of the Coal measure period, 
and hefore the New Red Sandstone began to be deposited. The 
seas of the Keuper were the first which washed the base of those 
hills and reached to all but their higher summits, so that there is 
nothing contrary to reason in finding some of these chasms filled 
with sediment of that age, and indeed it is probable that a much 
larger number of these fissures than is generally supposed, received 
