356 Mr. MuRCHisoN on the Strata of the Oolitic Series, ^c. 



g-neiss must then also have been in a state of softness. But, in whatever 

 mode these ramifying and tortuous veins in primary rocks may have been 

 produced, a very different explanation is requisite to account for the fractured 

 and brecciated beds of the oolitic series which accompany the elevation of the 

 granite on the coast of Sutherland. There, it is evident, that the granite, 

 when upheaved, could not have been in a fluid state, since it has neither pene- 

 trated nor overflowed the contiguous masses of solid breccia. In such situa- 

 tions therefore, the disturbing rock was, at the period of its elevation, most 

 probably in a compact and crystalline form ; in which case, when forced up 

 against the overlying strata, it must have fractured the sandstone, limestone, 

 and shale, thus preparing the materials which, when re-cemented, formed the 

 breccia above described. But we have additional evidence of the elevation 

 of the granite en masse upon this N.E. coast of Sutherland, where it has not 

 only brecciated the beds of the oolitic series, but has also thrown up the red 

 conglomerate to the summits of many of the mountains, whose bases consist 

 either of granite or of gneiss charged with granitic veins. In these positions, 

 the old red conglomerate which, when undisturbed, passes beneath the oolitic 

 series, and its coal-field of Brora, presents that anomalous appearance repre- 

 sented in PI. XXXI. fig. 2. which, without explanation, might lead to the 

 supposition of its being an overlying deposit. 



If an adequate cause be required to explain the great upheaving of the 

 granite upon this coast, may we not seek for it in some deeply seated volcanic 

 agency, struggling in vain to expand its forces from beneath the vast mass of 

 primary rocks of which the mountains in the north-eastern Highlands are 

 composed ? In reasoning upon this subject it is worthy of remark, that no trap 

 shows itself in association with primary rocks on the north-eastern coast. This 

 is however no objection to the hypothesis here started, for trappean or 

 porphyritic rocks may have acted upon the base of the primary mountains 

 as disturbing agents, without traversing the superincumbent mass so as to 

 appear on their surface. On the contrary, trap being developed to a prodi- 

 gious extent among the secowrfar^/ formations in the Hebrides and in the south 

 of Scotland, may it not be presumed that these latter deposits, owing to their 

 structure and their extent, were more easily traversed, altered, and even 

 obliterated by igneous operations of which they afford so many indications ? 



Red Conglomerate. 

 I offer no additional remarks upon the varied relations of that widely ex- 

 tended conglomerate which succeeds to the oolitic series, as it will hereafter be 

 treated of in detail by Professor Sedgwick and myself. But in relation to this 



