94 PEor. T. G. jjojsney's peteological notes on the 



I then returned to the well-known section at the lower end of this 

 " syenite " massif. The stream has cut a shallow hut picturesque 

 gorge in the crystalline rock, at the mouth of which the " limestone" 

 is well exposed by the water side. The former rock chiefly consists 

 of a pink felspar and a green micaceous mineral, with variable 

 amounts of quartz and a little epidote. Everywhere its aspect is 

 rather that of a metamorphic than a granitic rock *, the green mineral 

 in most places giving it a foliated structure, which strikes from about 

 W. 20° ^". to E. 20° S. in one part, to about N.E. and S.E. in another. 

 This is particularly distinct on the left bank, about 30 yards above 

 the junction with the calcareous series, where the rock is beyond 

 question a rather felspathic gneiss. 



On following the " syenite " up the slope of the right bank of the 

 valley we find a green serpentinous-looking schist emerging from be- 

 neath it. This, on microscopic examination, proves to be a true schist. 

 It consists of quartz and felspar, with opacite, viridite, and a fibrous 

 chloritic or hornblendic mineral, the amount of the green constituent 

 being less than, from the colour of the rock, one might expect. 

 It exhibits a very marked fragmental structure ; but this I strongly 

 suspect to be due to crushing in situf. 



The beds of the quartzose and calcareous series near the river dip 

 to about S.S.E. at angles varying roughly from 20° to 30°. Some 

 100 feet up the slope the angle is 37° S.S.E. Eurther down the 

 stream the dip changes nearer to E., and there is a roll over. I care- 

 fully examined the relations of the " syenite " and of the calcareous 

 series, and could not find that they exhibited any of the ordinary 

 indications of the junction of an intrusive igneous and a sedimentary 

 rock. In most of such cases that I have examined (and they are 

 many), where the former rock is coarsely crystalline, the line of junc- 

 tion is firmly welded and usually found with ease, if a fair surface of 

 rock be exposed. Here, though the two rocks could often be seen 

 almost touching, no contact- specimen could be discovered, and every 

 appearance indicated that the junction is a faulted one. Neither of 

 the rocks changes in mineral character on approaching the boundary ; 

 both appear rather crushed J; and this structure becomes very 

 evident on microscopic examination, one of the specimens appearing 

 singularly like an angular quartz-felspar gxit §. After much careful 



* I do not refer here to foliation only, but a peculiar indefiniteness in the 

 outlines of the crystalline constituents and other characters. 



t Eoughly on the strike of the above, and higher up the hill, a rather schisty 

 grey rock appears to be overlain by the " syenite." There is, however, nothing 

 incompatible with this being a member of the newer series (which microscopically 

 it resembles more than the older) locally nipped by the latter. So that I do not 

 think this one very dubious case sufficient to shake the body of evidence in 

 favour of the non-intrusive character of the "syenite." 



J The " syenite " is evidently much shattered, and is cut by numerous veins with 

 quartz, felspar, epidote, &c. 



§ It is obvious that this structure (very visible in three specimens, selected 

 from near the line of junction) presents to upholders of an igneous origin for 

 the " syenite" the following dilemma : — If it is not the result of crushing, but 

 an original structure, cadit qucestio ; if it is, then it ia a most exceptional struc- 

 ture to be found near an igneous junction. 



