AND THE ADJOINING DISTRICT, BERWICKSHIRE. 39 
with the secondary strata along the flanks of the Lammermuirs, belong as exclu- 
sively to the Augitic fumily. In considering these, we shall follow the natural 
order, by describing, Ist, the Felspathic traps, and their effects upon the grey- 
wacke strata; and, 2dly, the Augitic, or more modern traps, and the effects 
which they have produced upon the more ancient rocks, both stratified and un- 
stratified. 
1. Felspathic Traps. 
Rocks of this class are very abundant among the Lammermuirs, generally 
occurring in the form of dykes or veins of various sizes, intersecting the grey- 
wacke; or in large masses constituting entire hills. They consist of two or three 
varieties of granite and syenite, with an almost endless variety of felspars, clay- 
stones, and felspar porphyries. The following are some of the principal rocks of 
this kind which occur in the district. 
Granite of Cockburniaw and Staneshiel_—This rock shews a great variety of 
aspects at different parts of these hills. Near the outskirts of the mass, where it is 
in contact with the greywacke, its constituent crystals are very small, and its 
cleavage structures rectangular, and according with the strikes and cleavages of 
the adjoining strata. On proceeding into the interior of the mass, however, the 
rectangular cleavages due to its refrigeration, in accordance with certain lines, are 
superseded by the structures resulting from the crystalline tendencies of the 
granite, which have of necessity had more time for their proper development, in 
proportion as the distances from the cooling surfaces increased. The rock, in 
consequence, becomes harder, and its crystals larger and better defined, while it 
is divided by its structural planes into large, irregular, pyramidal blocks. Its 
most common character is that of a regular granite, composed of distinct crystals 
of white quartz, red felspar, and black mica; being identical, both in regard to 
geological age and lithological aspect, with a granite which is associated with 
greywacke near Fassney Bridge; and which, from being intruded among the 
strata of the latter, in conformable beds, caused much discussion between the 
Huttonians and Wernerians. In some places, as, for example, on the south side 
of the Staneshiel, about half way up the hill, sulphate of baryta is added to the 
usual ingredients of the granite; and near the top of that hill small quartz veins 
- occur, containing galena and copper pyrites, though in very minute quantity On 
the left bank of the Whiteadder, about 60 yards below Cockburn mill-dam, a 
mass of syenitic rocks of extreme hardness appears in contact with the grey- 
wacke, and projecting into the bed of the river. ‘This is evidently a process from 
the Staneshiel hill, the granite of which, as well as that of Cockburnlaw (which 
is indeed a part of the same mass), in many places passes into syenite. In fact. 
after an attentive consideration of the phenomena presented by the transition of 
one rock into another, and especially the changes effected upon both aqueous and 
igneous rocks, at and near their junctions, of which many highly instructive 
