230 Occurrence of Boulder Clay at H udder sfield. 



would thus deposit in these Yorkshire valleys, rocks of the 

 same formations as those which the valleys themselves are 

 composed. 



The deposits already found suggest that the ice entered 

 the cirque at the head of the Holme, and passing eastward, 

 overrode the spur at Wooldale, entered the Valley at New 

 Mill, then ascending the slope to Fulstone, passed through the 

 gap (650 feet) between Haw Cliffe (950 feet) and Snowgate 

 Head (900 feet) and so down the Kirkburton Valley. A 

 branch passing down the Holme might have given off a lobe 

 which, ascending the slopes of Lud Hill, passed over Farnley 

 Hey (675 feet), entered the Mollicar Valley and joined the 

 main flow at Woodsome Mill ; from thence its course would be 

 to Fenay Bridge and Dalton Lees, where it would merge with 

 the flow coming down the Valley of the Colne. Such a course 

 would account for the deposits as above recorded, and the 

 hypothesis will serve to indicate the lines along which further 

 evidence may profitably be sought. 



In the papers above referred to by Jowett and Muff and 

 Lower Carter, another problem involving this area is briefly 

 dealt with. These geologists carry the lateral moraine of the 

 Aire glacier southwards across the Calder at Horbury, and if 

 Carter's view is correct, the embankment was high enough 

 to hold up the Calder drainage to such an extent that its over- 

 flow channel near Wooley Edge was, at its lowest point, four 

 hundred and five feet above sea level. 



The lake also received part of the Aire drainage, which made 

 its way along a pair of successive channels near Wibsey, and 

 entered the lake at the head of the Spen Valley. 



A dam of the kind suggested would produce a lake of 

 truly fine dimensions, concerning which, however, some geolo- 

 gists are sceptical. If the area which would be covered were 

 indicated on a map, ' Lake Calderdale ' would be seen to 

 extend from Horbury to Todmorden (about 22 miles), and 

 would submerge much of the Spen Valley, also Batley, Dews- 

 bury, Ravensthorpe, Mirfield, Huddersfield, Brighouse, Elland, 

 Sowerby Bridge, Hebden Bridge and the intervening lowlands. 



One of the difficulties raised against the former existence 

 of such a lake, is the absence of records of laminated clay, so 

 characteristic of other lake deposits. Although searched for 

 in the sections recently exposed, I have not found any clay 

 of this type. Those who have doubts about this lake, however, 

 agree that the Humber drainage was blocked by the North Sea 

 ice to a height of at least two hundred and seventy five feet. 

 The lake which would thus be formed would include much of 

 the area of ' Lake Calderdale,' still laminated clays are ap- 

 parently absent ! But if the boulder clay is so obscured 

 and fragmentary as to have escaped the notice of glacialists, 



Naturalist, 



