84 Mt Stevenson on the Geology/ of 



of 100 feet above the level of the sea. At the north-western 

 extremity, or that most sheltered from the sea, there is a beach 

 called the White Bay, consisting of shingle ; while at all other 

 points the rocks expose surfaces varying from low angles up to 

 the perpendicular. There is but a thin covering of sod over 

 the surface, below which may be found angular fragments of 

 the mouldering rock, embedded in loam or earth resulting 

 therefrom ; and lying on this are erratic boulders of granite, 

 compact felspar, and porphyry, as well as a few water- worn 

 pebbles of greywacke. 



The rocks themselves* consist of beds of greywacke, alter- 

 nating with conformable greywacke slates, or, as they are there 

 termed, Slate-band. The greywacke beds vary in fineness, from 

 the coarsest conglomerate or breccia, up to a nearly homoge- 

 neous blue and sometimes greyish rock. And first, I may 

 notice the composition of the conglomerates, which consist of 

 water-worn boulders of greywacke, embedded in a softish 

 matrix of the same rock, or at least in an argillaceous rock of 

 very similar description. This may perhaps favour the con- 

 clusion that these deposits belong to the more recent of the 

 transition class. With regard to the breccia, it is proper to 

 state that it should more strictly be termed a hreccia-conglo^ne- 

 rate, as it consists of embedded fragments, partly angular, partly 

 rounded. These conglomerates are often permeated by veins 

 of yellowish, and sometimes red carbonate of lime, tinged pro- 

 bably by manganese. 



Next in fineness comes a very coarse greywacke, consisting 

 of small pebbles of quartz, fragments of jasper, Lydian stone, 

 pieces of clay-slate, &c. This rock is pervaded with dries, 

 which separate it into triangular prisms. The other grey- 

 wackes have all a rhomboidal fracture (of from 70° to 80° 

 obliquity), and are of various degrees of fineness, and invari- 

 ably shew specks of mica. They are all more or less cut up 

 by dries or cutters, and are also pervaded in every direction 

 by what appear to have been cracks or splits, which are occu- 

 pied by carbonate of lime tinted red. These cracks, some of 



* For a description of the rocks found in tlie Stewartry of Kirkcudbright, 

 ■ee the writings of Professor Jameson and of the late Mr R. J. II. Cunningham. 



