Vol. 51.] CRUSH-CONGLOMERATES OF THE ISLE OF MAN. 573 



is seen in the high crags of the western side of the main valley 

 1| mile farther north, where the rock is quarried for road-mending; 

 .and again on the opposite side lower down, still traversing the con- 

 glomerate, but there passing out also into the unbroken strata (see 

 section, fig. 9, p. 574). 



North of Druidale for a space the sections are not so clear, but 

 the brecciated zone may be traced crossing the stream at the Tholt- 

 e-Will bend and ascending the steep valley-wall on the northern 

 side, above the schoolhouse. 



From this point there appears to be an increasing tendency in the 

 structure to split into slightly divergent, though on the whole 

 parallel, bands, with expanding wedges of highly contorted, but yet 

 unbroken, slates between them. Of several possible reasons for this 

 arrangement, I am inclined, after consideration of the whole of the 

 evidence, to adopt the view that it is due in this area to the later 

 folding of an original plane. Many of the facts might, perhaps, be 

 .-as well explained by overthrust — or even by normal faulting, or 

 by the concurrent formation of the conglomeratic structure in the 

 equivalent limbs of a parallel series of folds. But the wide hori- 

 zontal spread of the material on the high land between Sulby Glen 

 and Ramsey (see map, PI. XIX.) seems to indicate the existence in 

 this region of a definite brecciated plane ; and with the abundant 

 evidence that earth-movements continued long after the making of 

 the conglomerate, the distortion of any plane formed at that early 

 stage appears almost inevitable. 



Prom the crest of the ridge just above the Tholt-e-Will schoolhouse 

 we may trace the main branch of the conglomerate, through the 

 broken ground around Craigmooar, to its junction with the Sulby 

 valley again on the northern side of the bend. Gritty flags, well seen 

 under Sharragh Bedn, lie, as usual, to the west of it ; while on the 

 •east there is a crumpled mass of dark argillaceous material with 

 an imperfect cleavage, which forms the left wall of the Sulby valley 

 in the elbow and has been extensively quarried on the opposite 

 bank at Ballaskella. 



East of this mass of slate another band of the crush-material is, 

 however, met with in the beds of the streamlets which descend 

 into Sulby Glen from the east. The sections are insufficient to show 

 the relation of this to the main band, but I think it may be regarded 

 .-as the partial emergence of the crest of a fold, though in that case 

 the plication of the plane must be rather acute. 



North of Ballaskella the main band is almost continuously ex^ 

 posed in the precipitous and somewhat inaccessible crags of the 

 western side of the valley. Its base at first forms only the crest of 

 the wall; but under Killabraggah this descends rather sharply to the 

 level of the river, and the upper limit of the conglomerate is then 

 found to fall just below the top of the slope, giving a vertical depth 

 at this point of between 250 and 350 feet. If the zone be steeply 

 inclined, however, its true thickness may fall short of this. Farther 

 north, as we shall see, both its extent and thickness are considerably 

 greater. 



The trend of the river below this point carries it again gradually 



