HUGHES : INGLEBOROUGH. 
269 
Scars, Amphitheatres, aind other Structural Details. 
The structure which seems most commonly to give rise 
to scars is the occurrence of rock, which spUts chiefly along 
the bedding, resting upon rock which breaks more along the 
joints. For if the vertically- jointed beds are exposed they 
are apt to break off, covering the base of the precipice with 
talus and crumbling down the still exposed edge of the cliff 
(see Plate XXXIII., Fig. 1). There is never a vertical cHff 
behind the talus where the form of the surface would probably 
be, as in the case of a chalk cliff, parabolic,* a point which it is 
useful to bear in mind in cave hunting. 
When, however, the jointed rock is capped with flat masses 
of unbroken limestone, perhaps with thin partings of impervious 
clay, they throw the water off, and the effect is to produce 
overhanging ledges from beneath which the more jointed rock 
weathers out. 
The- effect of these scars is well seen as we look out from 
Trowgill across the valley (see Plate XXXI.), and the bird's- 
eye view which we get from the higher ground further north 
enables us to see exactly the distribution and limitation of 
the higher beds left on the top of each spur. For here there 
are thinner beds of a light grey limestone occurring sometimes 
in a tabular mass with steep sides, but more often, especially 
in the lower part, chamfered off all round. In these fossils are 
fairly abundant, Chonetes being especially conspicuous as the 
rock splits along its flattened white shell. Producta Martini 
and P. striata occur here also. 
A little above 1,200 feet contour, on the way to the path 
among the Long Scar clints which is known as Clapham Lane, 
there is another example (see Plate XXXIIL, Fig. 2), on a 
much smaller scale, of the tabular bedded limestone resting 
upon vertically jointed rock, and forming a marked feature for 
some distance. The boy, holding a five-foot alpenstock, gives 
the height. Above this we rise by steps and terraces almost to 
the top of the Crey Mountain Limestone, which extends irregu- 
larly in bare, joint-riven, weathered rock from 1,200 to 1,300 feet 
* ct. Fisher, Geol. Mag., Vol. Ill, 186(3, p. 354. 
