SPENCER: GLACIAL BOULDERS IN CALDERDALE. 77 
formed a barrier equal to the rocky chain itself. In the deep 
hollow in which the town of Todmorden now stands and the many 
deep dales around, the local ice would be held in a compact mass, 
and the peculiar configuration of the ground would have a tendency 
to retain and preserve the local ice, nearly if not quite up to the 
general level of the Pennine Chain; so that the main body of the 
Lancashire glacier would be effectively _prevented from passing 
through these passes into Yorkshire. Nevertheless, both Captain 
Aitken and myself were satisfied that our Calderdale boulders of 
granite, etc., had somehow and by some means come over the 
Pennine Chain, and somewhere near the Walsden pass. We had 
assured ourselves of this by a careful examination of our Calderdale 
boulders and by comparing them with those of East Lancashire. 
When I first began to study this most interesting subject, having 
no particular theory of my own to support, I naturally inclined to the 
one which appeared to me to be the most plausible, and which 
seemed to be supported by the greatest weight of evidence and 
authority within our district, and that was the theory, that our 
Calderdale boulders had come from the east. Very early in my 
geological rambles I found a limestone boulder almost entirely full 
of small Rhynchonellz near Widdop’s Cross, at the height of about 
1,200 feet above sea-level, on the southern flank of Boulsworth Hill, 
and a short distance on the Yorkshire side of the boundary line 
between Yorkshire and Lancashire. This boulder and its enclosed 
shells strongly reminded me of a very similar limestone boulder 
which only a short time previously I had met with on the Yorkshire 
Coast at the foot of Castle Hill, Scarborough. The Rhynchonella 
found in the Widdop boulder appeared to me, and also to those persons 
to whom I showed them, to be closely allied, if not identical, with 
Rhynchonella socialis of the oolitic boulder from Scarborough Castle 
Hill. At my request, Captain Aitken took some of the Widdop boulder 
and its inclosed shells and submitted them to some great authority, 
probably Mr. Davidson, who declared the fossils to be a Rhynchonella 
from the Mountain Limestone. This settled the matter, and it was 
evident that this boulder had come over the ridge at Widdop’s Cross 
from Cant’s Clough, where a large number of limestone boulders 
may still be found, and not from the east-as I had imagined. These 
limestone boulders are very rich in Mountain Limestone corals, 
encrinites, producta, spirifera, etc., and they occur in great numbers 
On the north end of the Burnley (Cliviger) Pass, and also all around 
the flanks of Boulsworth Hill and the upland valleys in that 
neighbourhood, where they have in former days been largely used for 
burning into lime. This locality seems to have been occupied in the 
March 1893, 
