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



575 



merits (see fig. 10), which I take to be an indication of sharp folding of 

 the crush-material. I noticed also a few instances wherein a well- 

 defined inclusion was itself composed of breccia, of a texture and 

 tint different from that of its matrix, as though portions of a mass 

 already reduced 



to the state of Fig. 10. — Part of a crag in Sulby Glen (100 yards 

 crush - conglo - north of ' Limekiln,' Glen Mooar, 6-inch map). 



merate had (Length^ about '6 feet.) 



been again bro- -^ E 



ken up. At the 

 north - western 

 margin of the 

 zone, where the 

 contorted flags 

 begin to re- 

 sume their con- 

 tinuity, there 

 are some nar- 

 row strips of the 

 disrupted rock 

 interbedded 

 with compara- 

 tively unbro- 

 ken bands, as 

 though the 

 brecciation had 

 commenced and 





ff^i 





This section shows fragments in crush-conglomerate, with 

 linear arrangement suggestive of a broken overfold. 

 The larger inclusions are of pale-greyish flagstone or 

 fine grit, 1 to 3 inches in diameter. The slaty ground- 

 mass is crowded with smaller fragments. 



spread more readily along certain selected beds. The later shear- 

 cleavage is also strongly developed in the section. (Sec Mr. Watts's 

 Appendix, p. 591, & PI. XX. figs. 1-4.) 



The igneous dyke which cuts the crush-conglomerate at this 

 place has already been referred to. It is well exposed in the lower 

 crags above the junction of the streams, and may be followed thence 

 continuously for about 150 yards, where it passes from the crush- 

 material to the unbroken slates, among which it may be obscurely 

 seen at intervals for 300 yards farther. It is from 10 to 20 feet 

 thick. (See Mr. Watts's Appendix, p. 596.) 



The width of outcrop of the crush-conglomerate in these crags, 

 measured across the strike, is slightly over 400 yards, and its 

 vertical depth exceeds 500 feet, the top being lost in the grassy 

 ground beyond the valley-slope. 



The fine ranges of crags on the opposite side of the valley which 

 descend from the summit of Mount Karrin(1084 feet) are composed 

 of contorted flaggy grits with slaty partings, and are evidently con- 

 tinuous with those which flank the crush-conglomerate. They 

 exhibit many beautiful shear-structures not far removed from actual 

 brecciation, among which are many fine examples of the parallel 

 plication and partial fracture of the bedding which so closely 

 simulate ripple-marking on the surfaces of the more flaggy layers 

 (see fig. 4, p. 571). It is probable that many of the so-called ripple- 



