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Limestone are to be accounted for by a combination of fault and 
anticlinal which I shall presently describe. 
Such then has been the course of scientific opinion on the subject 
we are considering, and it appears to range itself under three 
heads. 
1st.—The original fault theory of Dr. Buckland. 
2nd.—-(Although third in order) the combined fault and anti- 
clinal theory of Mr. H. B. Woodward. 
3rd.—-The overthrow theory maintained by the various writers 
already referred to, 
I.—The Fault Theory.—When this was first suggested the Coal 
Measures in the vicinity of these isolated Limestone areas had 
been little explored. Numerous small shafts had been sunk here 
and there along the edge of the valley, but the Measures had not 
been developed in any connected or extensive way, and it is difficult 
to discover from what data the Ordnance geologists mapped with 
xo much apparent precision the faults indicated on their plans and 
gections. In order to convey a clear idea of their views I have 
prepared an enlarged copy of those portions of the Ordnance 
maps which bear upon the question, from which you will observe 
that the Luckington patch is shown to be completely hemmed in 
by faults. At each end of that area are indicated north and south 
faults extending from Cherry Garden to Leigh on Mendip, and 
there are east and west faults along each side. In the case of the 
Upper Vobster Limestone also a north and south fault is shown 
at the western extremity of the patch.* 
In the corresponding section the Coal Measures at Vobster are 
represented to occupy a comparatively shallow undulating basin 
not exceeding 1,000 feet in depth, and by assuming an upheaval 
* The ordnance maps and sections being easily accessible these illustrations 
have not been added, and for similar reasons Mr. Woodward's sections (which 
are afterwards referred to) have beon omitted. 
