222 ON THE HOCKS OF SANDSIDE 



gneiss. Of these the syenite appeared to be the most 

 abundant. The granite occurred in veins and masses 

 in the syenite ; and the gneiss was only observable 

 in large and small cotemporaneous masses imbedded 

 in the syenite. The hornblende-rock, like the gneiss, 

 did not appear forming regular beds or strata, but 

 only disposed in masses imbedded in the syenite. 

 Many blocks of red-sandstone, and of granitic con- 

 glomerate, were observed in the' bed and on the 

 sides of the burn, but we did not discover them in 

 situ. We crossed eastwards over some low hills of 

 syenite and gneiss, to Reay Burn, and traced it to 

 its termination in the bottom of the bay. Every 

 where in its bottom, sides, and neighbourhood, 

 where, rocks could be seen, these were of syenite, 

 with hornblende-rock and gneiss. Several of the 

 beds or masses of the syenite, had a brecciated or 

 conglomerated structure, from the numerous rouend- 

 ish, blunt and sharp angular portions of hornblende- 

 rock distributed through them. We crossed the 

 small bridge over the burn, at the Manse of Reay, 

 and walked along the east side of the bay, towards 

 Isald Burn ; but, owing to the deep cover of loose 

 blowing sand, we did not discover any considerable 

 fixed rocks, until near the mouth of the burn, when 

 strata of grey quartzy sandstone, slate-clay, often 

 inclining to clay-slate, and coarse grey limestone, 

 frequently variously convoluted, made their appear- 

 ance. These strata continued to the extremity of 

 the bay, where they formed lofty precipices and 

 cliffs, facing the Pentland Frith. 



