232 LAW AND SIMPSON : DRIFT DEPOSITS AT MYTHOLMKOYD. 
And again, " An observer cannot fail to be struck with the 
contrast between the western and eastern sides of the Pennine 
Chain as regards the glacial deposits. All along the western 
flanks of the chain and extending into the plains these deposits 
are spread in masses, often attaining a thickness of 150 or 
200 feet, but on the Yorkshire side these deposits are absent, 
the strata everywhere appearing at the surface, or only covered 
by soil."^ 
It would appear, therefore, that these observers did not note 
the presence of drift with erratics at Mytholmroyd. 
So far back as about a.d. 1840, however, according to the 
late James Spencer f (who latterly somewhat boldly described 
these deposits as the "Mytholmroyd Moraine"), a considerable 
number of boulders of granite and other foreign rocks, some of 
them half a ton in weight, were found in making the railway 
between M3^tholmroyd and Hebden Bridge, the cutting for which 
traverses tlie length of the terrace. 
In later years many observers have recorded erratic rocks 
found at the surface, exposed in the footpaths, or at the foot 
of the terrace almost throughout its length.:;; 
The occurrence of glacial boulders in the Calder Valley, 
originating from Cumberland and the Lake District, is now, of 
course, well established by extensive finds at Millwood, near 
Todmorden, Mytholmroyd, Luddenden Foot, Sowerb}^ Bridge, 
Elland, Brookfoot, Mirfield, and elsewhere, and it is not unlikely 
that these glacial deposits occupy the bed of the valley from 
Todmorden to Sowerby Bridge, covered by more local drift and 
alluvium. 
In order more thoroughly to examine tlie nature of this 
Mytholmroyd drift and its contained erratics, a sub-committee of 
the Yorkshire Geological and Polytechnic Society was appointed, 
* Ibid, p. 133. 
t See Halifax Naturalist, Vol. I. , p. 21 ; also Proc. Yorks. Geo. and 
Poly. Soc., Vol. XIII., p. 375, section illustrating paper. 
J See reports of Yorkshire Boulder Committee for 1893, 1895, 1897. 
