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



coast must have been elevated at a period subsequent to the deposition of the 

 oolitic strata*/' but has also led Professor Sedgwick and myself to the con- 

 viction, that it has been upheaved in a solid form^ and that,, in breaking 

 through those submarine deposits which might not perhaps have been origi- 

 nally in contact^ it has so fractured and dislocated their beds as to have pre- 

 pared them for reconsolidation in the state of a brecciated rock. 



At the Ord of Caithness this granite occupies a vertical cliff upon the coast 

 for nearly two miles, throwing off the old red conglomerate on its northern 

 flank towards the plains of Caithness ; whilst to the south it forms a lower 

 and broken cliff somewhat within the sea line^ and which occasionally pro- 

 truding on the shore, exposes upon its edges the brecciated rock. This 

 breccia is exclusively derived from the oolitic series of this coast, the frag- 

 ments of which, consisting of shale, sandstone, limestone, and fossil organic 

 remains, are united into a compact mass by a calcareous cement; which, 

 near the Ord, has a stratified appearance, rising from ledges below the tidal 

 level to the height of fifty or sixty feet in the cliff, and dipping S.E. at a high 

 angle. Thence to Navidale the shore is formed of the breccia, and the cliff 

 of granite; but the latter is here so decomposed as to assume the general cha- 

 racter which induced me to apply the term "^ granitic rock" to the whole. 



The higher portions of the cliff are covered by thick diluvial accumulations 

 derived from the primary mountains of the interior. In one situation, well 

 crystallized granite protrudes upon the shore ; and there the brecciated beds 

 in contact with it are tilted at high angles, in various directions from the sub- 

 jacent points of the crystalline rock ; but as soon as the granite recedes inland, 

 the regular strata (the fragments of which form the breccia) begin to occupy 

 their regular places in the series exhibited on this coast. 



The extraordinary appearances accompanying a contact of the granite with 

 these deposits near Portgower have been cursorily noticed f ; but they merit 

 a more detailed description. The sandstone and shale rising from the shore 

 at a moderate inclination, occupy both sides of a ravine, where the superior 

 beds are first seen assuming arched and tortuous forms, apparently owing to 

 irregular and fractured masses of the lower beds, which are driven upwards, 

 and wedged vertically into overlying shale. 



On further ascending the stream, all the strata on both banks from the base 

 to the summit are observed to be broken up into countless fragments, and in 

 one part to form a conical hillock resting upon the granite which is disclosed 

 in the bed of the burn. These phasnomena seem clearly to prove, not only 

 that the granite has been elevated after the deposition of the overlying strata, 



• Ante, page 307. f Ante, page 306. PI. XXXI. 6g. 2. Portgower. 



