JOHNS : FAULTS IN THE SETTLE-MALHAM AREA. 397 
Langcliffe, and on the west of the valley runs at the back 
of the hill above Giggleswick, thus cropping out with a 
V-shaped outcrop, of which the apex points up the valle}^." 
Dr. Marr goes on to describe the occurrence of Knoll limestones, 
with a fauna similar to that of the Cracoe Knolls, south of the 
line he suggested for the fault and above Scaleber Force. Even 
this, however, does not explain the great discrepancy in thick- 
ness if measurements be made west of scar above Victoria Cave. 
Many observers seem to have suspected transverse faults, Upper 
Winskill in the west and Goredale to the east of our area being 
instances, but it does not appear that any records of their ob- 
servations have been published, or that any explanation of 
the observed difference in thickness of the Great Scar Limestone 
between and north of the faults has been offered. 
The Faunal Sequence. 
The previous workers, with the exception of Dr. Marr, 
who recognised the existence of Knoll limestones with their 
characteristic fauna, depended on lithological differences in 
determining the lines of dislocation. As this present account 
is based on palaeontological evidence in addition, it becomes 
necessary to give a brief description of the faunal sequence. 
The Great Scar Limestone can most conveniently be divided into 
two divisions, an upper and a lower. As exposed north of 
the faults it corresponds to the Visean of the S.W. Province 
and of Belgium. The lower division is distinguished by the 
absence of Giganteii producti and corals of the genus Dibuno- 
phyllum. The horizon where these enter, together with the 
associated fauna of which Cyrtina septosa is the most striking 
brachiopod, constitutes the base of the upper division. The 
lower division corresponds to the Seminula zone of Dr. Vaughan, 
while the upper corresponds to the Dibunophyllum zone. 
It is this base of the upper zone, with its first maximum 
of Productus " giganteus " and the Dihunophyllid corals, which 
has been used in this investigation as a faunal horizon, in the 
same way that one would have used a well-marked and per- 
sistent shale bed il such existed in the Great Scar Limestone. 
The value of such a faunal line depends on its persistence over 
K 
