JOWETT AND MUFF : GLACIATIO^N^ OF BRADFORD, ETC. 209 
taken by the striae is consistently from north-west to south-east, 
but that when they are found on the bottom or lower slopes of 
a valley, their direction more nearly conforms with the trend 
of the particular part of the valley in which they occur. A 
greater freedom of movement would be expected in the upper 
layers of a glacier than in the lower layers, which must mould 
themselves to the inequalities of the glacier-bed. Hence the 
high level striae more truly represent the direction of the general 
ice movement than the others. 
Several cases were noted where the scratches on large un- 
disturbed boulders were in the same direction as those on the 
neighbouring rock-surface. 
DETAILS OF STRIATED ROCK-SURFACES. 
(1) The surface of the Rough Rock exposed in the small 
quarries and on the roadside above Long Lee, one mile south- 
east of Keighley, is striated in several places.* The striae vary 
from fine scratches to broad grooves more than a yard long, 
and their direction is from N. 45^ W. to S. 45° E., a few crossing 
them from N. 65° W. The surfaces are not always plane, and 
the various prominences are striated on their north-west sides, 
whilst their south-east sides are rough. Each of the quartz 
pebbles on the surface of the grit is polished and finely striated 
on its top and north-west side. In one or two cases the general 
surface is not level, but dips northwards at angles varying up 
to 16°, so that the material which produced the grooves must 
have been dragged obliquely up the slope of the surfaces. Their 
altitude varies from 750 feet to 825 feet above O.D. 
(2) About three-quarters of a mile nearer Harden, and on 
the east side of the road, smoothed rock-surfaces may be seen 
grooved from X. 35° W. to S. 35° E. 
(3) The grit exposed in the cutting on the Great Northern 
Railway, half way between CuUingworth and Wilsden Stations, 
is striated from N. 50° W. to S. 50° E. The north-westerly 
sides of the inequalities of the surface are rather more deeply 
and abundantly grooved. 
* Indicated on the Geological Survey Map (1 inch 92, S.E.). 
B 
