PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 469 
writes :—“I am under the necessity of describing the next of the overlying 
ROCKS. .... On the sides of Halival and Haiskeval* it is found intermingled 
with the augite rock in large masses, nor could I after much research 
determine the precise nature of the relation between them. The character of 
this trap varies in different places. In one place there occurs a mass, of which 
the weathered surface displays imbedded fragments of the same rock. In 
another place there is a still more remarkable mass, consisting of an ordinary 
black basalt, with fragments of the red sandstone scattered at considerable 
distances through it. It is by no means common to find trap veins entangling 
fragments of the rock which they traverse. ... . Notwithstanding the difficulty 
of determining the exact nature and connection of these masses, it is probable 
they are portions of large veins, which the ruined and encumbered nature of the 
ground does not permit to be traced. This trap, therefore, is posterior to the 
augite rock and syenite, although it cannot properly be called superincumbent.” 
Though, as I have remarked, the inference to be drawn from MaAccuLocu’s 
observations must be that the hypersthene rock of Skye and the augite rock of 
Rum are mere modifications of the same rock, and that an zgneous one, such is not 
the conclusion which has generally been arrived at. ‘“Metamorphosed Laurentian 
gneiss” was the view at one time held. Dr Srerry Hunt, who appears to be 
the last writer who notices these rocks, in summing up the evidence regarding 
them (pages 279 and 281 of “Chemical and Geological Essays”), concludes 
that they are “identical with the North American norites, whose stratified 
character is undoubted.” He quotes Emmons in support of this view; and 
HavucutTon,—who regards them as evidently a “ bedded metamorphic rock.” 
“Stratified character” is not precise; neither is “ bedded metamorphic rock ” 
altogether so. An igneous rock may have a stratified character; and a bedded 
igneous rock may have suffered metamorphosis. 
These expressions, however, though by no means clear in themselves, are 
generally employed as contradistinctive of intrusive or eruptive ; and the con- 
text of the two pages mentioned, clearly shows that they were so used. 
STERRY Hunt's view, however, is evidenced by the following quotations :— 
“1 propose to designate as the Norian series the great formation of crystalline 
Stratified rocks, of which the norites make up so large a part.” 
“JT accept in its widest sense the view that all the crystalline stratified rocks 
have been produced by the alteration of mechanical and chemical sediments.” 
“Tn the second class of sediments we have” a series of specified chemical 
changes and crystalliferous admixtures, “which give rise to diorite, diabase, 
euphotide, eklogite, and similar compound rocks.” 
| This “second class of sediments,” or “‘ series,” is the Norites, which are 
_ placed below the Huronian, in which latter he includes the Cambrian, among 
| its upper members. 
* Aisgobhall of Jameson. 
VOL. XXVIII. PART IL. 6F 
