396 JOHNS : FAULTS IN THE SETTLE- MALH AM AREA. 
and a perpendicular dropped from that plane to the lowest 
exposed limestone at the boundaries of our area, we get an 
iipparent thickness which might be estimated at 1,200 feet. 
If the faunal horizon adopted as base of the Dibunophyllum 
zone be taken as the datum plane, a still greater thickness must 
be assumed, for the faunal line dips more steeply to the N. or 
N.E. than the top of the limestone. As the observed thickness 
of Great SCar Limestone north of the inner fault is about 500 
feet, the discrepancy is a very serious one. 
Previous Opinions. 
It is somew^iat difficult to discover what the older writers 
considered to be the actual line taken by the outer fault, in 
the absence of a detailed map, other than that it continued 
irom Giggleswick Scar past Ryeloaf Hill to Malham. Da vies,* 
in his description, mentions that 
" The limestone scar behind Settle is a continuation 
of the fault, and, still proceeding eastward, the grand series 
of scars of Attermire and Langcliffe, perhaps the finest 
along the whole line of dislocations, extend towards Malham. 
They form dr}^ hills to the left of the road, whilst to the 
right are wet surfaces of Millstone Grit, the road being 
near the line of fault." 
This would approximate to the line drawn by Mr. Tiddeman, 
the junction of grit and limestone being the chief point noticed. 
The only writer who seems to have suggested a radical change 
in the line mapped as the outer fault is Dr. Marr.f who came 
to the conclusion that this fault (the " middle " of his paper) 
represented a thrust plane, but as the line, as mapped, indicated 
the apex of the V pointing south gave reasons for drawing the 
fault line further north. 
" Examination of the area shows that the continuous 
scar which, I believe, marks the boundary of the fault, 
runs far north of this along the Settle and Beacon Scars 
(Attermire Scars), and so to the Ribble betw'een Settle and 
* Wesc Yorkshire, Davies & Lee, p. 7. 
t Q.J.G.S., Vol. Iv., 1899, p. 352. 
