1852.] NICOL ON THE GEOLOGY OF CANTYRE. 415 



reagglutinated into one mass. The rock is one of the most singular 

 breccias I have ever seen, and appeared as if the dome of basalt had 

 been shivered by a violent blow into innumerable fragments and then 

 again subjected to heat until these fragments partially adhered. 

 Some other examples of these formations will be subsequently noticed, 

 and I shall only add, that it is not in all cases possible to separate 

 the felspar series of rocks from those containing augite. They not 

 only occur together, but appear to graduate into each other occa- 

 sionally. 



The geographical distribution of these igneous rocks is shown ge- 

 nerally by the map, PI. XXIII. Their relations to the stratified 

 deposits vary considerably in different localities. Those seen in the 

 hills north of Campbeltown partly overlie, partly are intercalated 

 among, the limestone and slate rocks, and partly intersect them in 

 veins. The igneous formation in the south of the peninsula also oc- 

 casionally overlies or intersects the slates in beds or veins. More often, 

 however, it is connected with the red sandstones and carboniferous 

 strata of that district, which appear imbedded, as it were, among the 

 igneous rocks, in fragments the form and position of which I had not 

 the means of working out in detail. 



Some of the sections of these rocks are very interesting. One of 

 the most remarkable is exposed in the cliffs on the west coast about 

 a mile south of Losset. In this place a large outburst of igneous 

 rocks, sometimes amygdaloidal greenstones, at other times grey fri- 

 able tufas, full of veins of fibrous calc-spar or pure crystallized quartz, 

 overlies beds of reddish clay, resting on limestone, and this on sand- 

 stone. The sandstone near the igneous rock is much hardened ; the 

 limestone, of a greyish white colour, is nodular, concretionary, of a 

 saccharoid texture, and interlaminated with veins of calc-spar and 

 steatite. 



A little further south, the manner in which the trap has found its 

 way to the surface is very beautifully shown. The shore, where 

 laid bare by the waves, between high and low water-mark, consists 

 of beds of highly contorted mica-slate, dipping about 35° to S. 45° E. 

 Higher up, on the old elevated sea-beach, the rocks are concealed by 

 blown sand and the debris from the steep and lofty cliff above. This 

 cliff is formed of sandstone and limestone, which project in thick beds 

 from the turf. In the place represented in the accompanying figure 

 (fig. 2), two veins of trap run nearly vertically up the cliff; and are 

 again seen in a horizontal section on the shore intersecting the mica- 

 slate. The smaller vein, on the north, is about 4 feet wide, and is 

 a dark greenstone, divided into horizontal columns in the centre, but 

 with vertical laminae on the sides. In the sandstone its course is 

 nearly straight, but in the mica-slate it is very tortuous and irregular, 

 the contortions in the slate having probably caused the fissure to 

 assume a very rugged form. The larger vein is about 40 feet wide, 

 and is a grey porphyritic amygdaloid. In passing through the mica- 

 slate these veins do not seem to alter its usual characters, but merely 

 to fill a fissure in it. The smaller vein appears to spread out in a 



2 E 2 



