TRANSACTIOlJS OF SECTION C. 757 



sides of the main valley, are cut at right angles iu many places by notches trend- 

 ing from N.W. to S.E. 



2. Characteristics of the Olacial Deposits and Strice. 



Boulder Clay is found in many places throughout the area, and consists of a 

 tough blue clay which has a superticial covering of yellow sandy clay of very 

 variable thickness. The contained stones are chiefly Carboniferous limestone, 

 chert, grit, and sandstone, including gannister, together with shales and iron- 

 stone nodules. Occasional pre-Carboniferous grits and slates have been met with. 

 The limestone boulders become fewer in number and generally smaller in size 

 as we proceed down the main valley, and also as we approach the periphery of 

 the area from the main valley. Boulders of the other rocks are also found to the 

 .south-east of their solid outcrops. Most of the boulders in the blue clay are 

 beautifully moulded and striated. The yellow clay contains fewer limestones 

 than the blue, of which it appears to be simply the weathered crust. 



Gravel is often found above and at the margin of the boulder clay, and in 

 some places passes into current-bedded sands. Occasionally a section is seen 

 showing clay, sand, and gravel of all degrees of coarseness in interdigitating 

 layers. Sections at the lower ends of the spur-cutting notches above mentioned 

 have revealed current- bedded sands and gravels, &c., composed of materials similar 

 to the rocks exposed in the sides of the gorge above. Striae are most frequently 

 preserved on beds of grit which have a covering of clay ; one set was found on 

 gannister similarly preserved. In the case of the grit surfaces, not only are there 

 long parallel striations on the whole surface, but the larger quartz-pebbles are very 

 finely scratched in the same direction. The direction of the ice-movement was 

 deduced from the observation that surface irregularities were rounded and smoothed 

 on the one side, but rough on the other. 



3. Maximum Extent and Direction of Movement of Glacier. 



The floor of the Glusburn Valley is covered with boulder clay which is con- 

 tinuous with and similar to the drift on the western side of the Pennine watershed 

 described by Mr. R. H. Tiddeman. On Cowling Moor, along ridge of unstratitied 

 gravel, 50 feet thick, is seen at an altitude of 1,150 feet O.IJ. Great masses of a 

 hard conglomerate of limestone, grit, and shale occur, the cementing material of 

 which is calcite, evidently deposited from solution by percolating water. Above 

 this ridge, sandy clay with limestone and chert, as well as grit, gannister, &c., 

 may be traced up under the peat to 1,350 feet, and to a somewhat greater altitude 

 to the westward. Combe Hill (1,454 feet) was not overrun by the ice, its surface 

 being covered by the angular fragments of the underlying grits, and drift being 

 also absent from its southern and south-eastern slopes. On Boulsworth Hill, to 

 the south, drift is found up to nearly 1,400 feet. Thus, though the ice stood up 

 against these two hills, it did not actually force its way through the gap between 

 them. 



Tr.aced eastwards, the altitude of the margin of the drift diminishes, and it 

 continues to diminish all down Airedale. It reaches 1,250 feet onKeighley Moor, 

 and is traceable round into the Worth Valley above Ponden at 960 feet. On 

 Haworth Moor the limit is met above Leeshaw Reservoir, and south-west of 

 Leeming, at just above 1,025 feet. No traces of glaciation occur on Oxenhope 

 Moor and Thornton Moor above Denholme ; but the ice pushed round into the 

 Harden Valley, leaving a marginal moraine at Hallas Rough Park (900 feet) con- 

 sisting of boulder clay, gravel, and sand heaped up in ridges running from N.W. 

 to S.E. The Harden Valley contains boulder clay as far as Denholme Station. 

 Clay is also found in the Wilsden Valley and up the face of Harrop Edge to over 

 925 feet. Drift around Allerton shows that the ice pushed over Chellow Dean 

 into the Bradford Valley, laying: down thick deposits of tough clay, with many 

 scratched limestones at Ilorton Grange, and reaching up to the summit of the ridge 

 separating Airedale and Calderdale at Wibsey Bank Foot. The drift-filled valley 

 s«en in section near Low Moor Station points to the conclusion that, at the extreme 



