572 



MR. G. W. LAMPLUGH ON THE 



[Nov. 1895, 



later date, produced separately from and independently of the 

 brecciation-movement, sometimes cuts and sometimes avoids the 

 grit-fragments (see figs. 7 & 8). (See also Mr. Watts's Appendix, 

 p. 594, & PI. XX. fig. 5.) 



In the bed of the main stream, only a few yards distant, the 

 inclusions are much larger in size ; among them are some fragments 

 of coarse-grained 



Fig. 7. — Crag on northern slope above Druidale 

 stream, at junction with Sulby River. 



{Length = about 3 feet.) 



W. N. W. 



E.S.B. 



grit ; and they are 

 mostly quite len- 

 ticular and often 

 preserve in their 

 interior traces of 

 their proper bed- 

 ding. 



In the crags a 

 dyke of igneous 

 rock of the ' green- 

 stone ' or diabasic 

 character is seen 

 among the conglo- 

 merate. This must 

 have been injected 

 after the breccia- 

 tion of the slates, 

 since it is itself 

 unbroken and 

 moreover slightly 

 alters the conglo- 

 merate surround- 

 ing it. Yet it has 



undergone pressure sufficient to develop an obscure cleavage, 

 probably equivalent to the later shear-cleavage just described ; and 

 of an originally porphyritic constituent there remain now only 



Pig. 8.- — Part of crag on northern slope above Druidale stream, 

 near junction ivith Sidby River. (About ^ nat. size.) 



The crush -conglomerate has a shear-cleavage z-z 

 obliquely crossing the long axes of the grit-frag- 

 ments. The section is along the strike of the 

 shear-cleavage, which dips N. 20° E. at 35°. The 

 broader faces of the grit-fragments are dipping 

 to N.W. Their maximum diameter, in this section, 

 is 2 inches. 



Crush-conglomerate, with the later shear-cleavage planes in the shaly ground- 

 mass partly swerving around, and partly crossing, included fragments of 

 fine-grained grit. 



smeared blotches of greenish chloritic material. These facts seem 

 to require a definite interval for the injection of the dyke, after the 

 brecciation-movement and before the development of the ' shear- 

 cleavage.' I suspect that it is a continuation of this dyke which 



