146 ASSOCIATIONS OF [Ch. VIII. 



crystalline schist, under various circumstances, and in different 

 forms ; so likewise the latter rocks occur in detached portions 

 in the granite, not only at the junction, but in the main mass 

 some distance therefrom. 



Examples of this kind in Cornwall are on a very small 

 scale, and of rather an obscure nature : at the junction, in- 

 deed, portions of slate are entangled with, or even enveloped 

 in, the granite ; but even in this position they are not always 

 very distinct, owing to the slate being of a compact and 

 crystalline character, not readily distinguishable from the 

 granite, when this rock has not its ordinary appearance. In 

 every portion, however, of the granitic mass, small concretions 

 may be observed, which have a dark colour and compact 

 texture, owing, apparently, to the constituents of the granite 

 being, at such points, very fine-grained, and intimately united 

 with black mica, shorl, pinite, or other minerals, which are 

 more abundant than in the general mass, attracted as it were 

 round certain centres. But these appearances are better 

 displayed in some other countries. 



In various parts of Galloway, Sir James Hall observed 

 portions of slate in the granite at the junction of these rocks : 

 at the Hill of Lauren, " the granite actually contains a mass 

 of the stratified body included in its substance;" and "in 

 the island upon which the Castle of Doon stands, angular 

 fragments of killas are surrounded on all sides with granite." * 

 And on the shores of Loch Doon, Dr. Grierson observed 

 fragments of compact gneiss in the granite, which is here a 

 common and prominent feature, but of more rare occurrence 

 in the Dee district : " one of these fragments, of a tabular 

 shape, was two feet long, about ten inches broad, and four 

 in thickness. Some of them have disintegrated more rapidly 

 than the granite, and so have left hollows in it, and have, 

 indeed, fallen out : others have weathered more slowly than 

 the surrounding granite, and are seen projecting from the 



t * Royal Trans, of Edinburgh, vol. vii. p. 102. 



