320 J. W. Dart's — Erratic Boulders of the Calder Valley. 



Colne. It is quite impossible that these could have come from the 

 west ; the river rises on the high moorlands of Millstone Edge and 

 Holme Moss, nearly 2000 feet above the sea-level, and falls rapidly 

 to its confluence with the Calder at about 200 feet above the sea-level. 



Some other peculiar circumstances may possibly be accounted for 

 if we suppose the land to have been submerged to about 400 feet 

 lower than its present level, and at the same time these facts act re- 

 ciprocally in affording evidence that such was really the case. There 

 are numerous beds of gravel and well-rounded boulders, composed 

 entirely of rocks of local origin, millstone grit, flagrocks, pieces of 

 coal, and the harder shales, and, where the peculiar siliceous sand- 

 stone called Calliard occurs in the vicinity, it is found in the gravel 

 or drift. These beds occur on the hill-sides bounding the valleys, 

 and generally at a height of 350 feet, a little more or less, above the 

 present level of the sea. Examples may be seen at Kirklees Park, 

 near Mirfield, at Exley. in the Elland Cemetery, at Mytholm, in a 

 branch valley west of Halifax, and in other places as far westwards 

 as Hebden Bridge. These gravels are quite distinct from those in 

 the bottom of the valley, and are usually found occupying a plateau 

 formed by a gritstone, from which the softer superincumbent shales 

 have been denuded. In each of the situations cited above they are 

 at least a hundred feet higher than the present level of the valley. 

 Where exposed in section, they are current bedded, with thin layers 

 of sand intermixed, and present every appearance of having been 

 subjected to tidal action. The presence of these beds has been 

 accounted for in a variety of ways ; but the one I now suggest — 

 that they were the shores of the old sea — perhaps appears the most 

 reasonable, when considered in connexion with the drift deposits 

 filling up the base of the valley. If they are the remains of the 

 shores of an old lake, as some authors have described them to be, 

 there remains the difficulty of damming up the waters to so great 

 a depth, which does not appear probable, and of which there is 

 no evidence at present existing. 



In conclusion, the evidence that the erratic boulders in the valley 

 of the Yorkshire Calder were derived from the sources so plentifully 

 supplied in the great valley occupying the whole of the centre of the 

 county, rather than from the district westwards of the summit of 

 drainage, appears conclusive. In the one case we have the source 

 of the Calder bounded by a series of hills rising to a height of 1,500 

 feet or more, and the only openings being at Calder Head on the 

 northern and at Hollingworth on the southern part of the Chain. 

 In either of these the land rises rapidly from the Lancashire side to 

 the height of 610 feet and 700 feet respectively, and in each case 

 they form the summit of drainage. All evidence proves that the 

 general form and direction of the valleys remains unchanged since 

 pre-glacial times, and this being so, the ordinary action of rivers 

 being the agent which has carried the boulders from the Lancashire 

 districts over the summits of drainage may be dismissed as out of 

 the question, and, along with it, the theory of some of the early 

 geologists, of a great wave of translation which was supposed to 



