part 4] NORiTE or sierra leoxe. 3091* 



features has been noted also in the gabbro of the Cuillin Hills by 

 Sir Archibald Geikie and Dr. A. Harker,^ and in the Carrock-Fell 

 gabbro by the latter. ^ 



In many localities the grey surface of the norite shows numerous 

 ill-defined brown and black spots : the former being composed of 

 pyroxene and felspar in ophitic relation, and the latter of spongy 

 growths of magnetite. 



The principal intrusions into the normal rock are: — (1) the- 

 younger norites; (2) norite-pegmatite ; (3) beerbachite ; (4) norite- 

 aplite; and (5) dolerite ; but, in addition to these, there are two 

 series of veins and a felspar-olivine rock, all, however, of rela- 

 tively little importance. I may now briefly describe these smaller- 

 intrusions : — 



The veins may be divided into two series, according to their 

 age and occurrence. 



(a) The veins of the first series occur in the older norite; they 

 have ill-defined margins and a complex branching and tapering 

 habit which causes them, to weather into a rough network on an 

 exposed surface. An example of this may be seen on the foreshore. 

 at Kent opposite the Court House. The veins rarely exceed. 

 2 inches in width ; they are generally less basic than the enclosing- 

 rock, and are of rare occurrence as compared with the veins of the- 

 later series. They closely resemble the segregation-veins figured 

 and described in the Skye Memoir (p. 78). 



(Z>) The veins of the second series are related in occurrence and 

 in composition to the younger norites ; they are consequently 

 younger than those of the first series, and may sometimes be seen, 

 to cut them. They are distinguished from the segregation-veins 

 by their composition, by the inclusion of ragged black bronzites 

 measuring up to an inch in diameter, by their sharper margins,, 

 more regular form, and greater width. 



The felspar-olivine intrusions consist of a tough pale-green 

 rock of medium texture, rich in olivine and containing numerous 

 small black grains of iron-ore. One of its best exposures is near 

 the foot of Charlotte Falls, where it forms a small lenticle in the 

 normal norite about 4 feet thick. 



Exposures. 



(i) Murray Town, foreshore. — Normal norite banded and spotted,, 



and traversed by black pyroxenic veins, 

 (ii) Aberdeen Creek, foreshore. — Southern point: the norite is 



banded and highly ferruginous ; it contains numerous seams rich 



in magnetite, and the laterite resting upon it is a good hsematite-ore. 

 (iii) Sussex, foreshore. — Flow-banding well developed; some bands 



show crushed felspars, others consist largely of coarse granular 



olivine. 



1 ' The Tertiary Igneous Eocks of Skye ' Mem. Geol. Surv. 1904, p. 91. 



2 ' Carrock Fell ; a Study in the Variation of Igneous Rock-Masses : Part I 

 —The Gabbro ' Q. J. G. S. vol. 1 (1894) p. 319. 



