290 
VOLCANOES OF THE LOWER OLD RED SANDSTONE book v 
notable are the bosses of granite and other acid material which rise throirgh 
the Silurian strata of the Southern Uplands of Scotlaudd The largest are the 
well-known masses of Galloway (Fig. 69), with which must be grouped the 
bosses near New Cumnock, that of the Spango Water (Fig. 94), and those of 
Cockburn Law and Priestlaw in Lammeriuuir, together with a number of 
masses of felsitic material scattered over the same region, such as the Dir- 
rington Laws of Berwickshire (Fig. 7 0). These bosses present some points of 
structure in common with true vents. They come like great vertical columns 
through highly-folded and puckered strata, and, as they truncate the Llan- 
dovery and Wenlock formations, they are certainly younger than the greater 
part of the Upper Silurian series. They must be later, too, than the chief 
plication and cleavage of these strata; but they are older than the Upper 
Old Red Sandstone or basement Carboniferous rocks which contain pebbles 
of them. Their date of eruption is thus narrowed to the interval between 
the later part of the Upper Silurian period and the beginning of the Upper 
Old Red Sandstone. T have myself little doubt that they are to be asso- 
ALerrick. Mnllwhardiar Corseruic, 
Fig. 69. — Section of the granite core between Merrick and Corscrine. 
ff, Silurian greywackes, grits and shales ; 5, granite. 
dated with the volcanic epoch we are now considering, as it was the only 
known great episode of igneous activity in this region during the interval 
within which the protrusion of these granites must have taken place In 
the Cheviot Hills, indeed, we have evidence of the eruption of a large 
mass of airgite-granitite through the porphyrite-lavas of the Lower Old Red 
Sandstone, with abundant veins projecting from it into them, as will be 
narrated in later pages." 
Not improbably many other granite protrusions throughout the British 
Isles are to he referred to the volcanic operations of the Lower Old Red 
Sandstone. Such are those of the Lake District, notably that of Shap,® the 
granites of Newry and Leinster in the east of Ireland, which are later than 
the Silurian rocks and older than the Carboniferous Limestone, and the 
younger Grampian granites, which pierce the presumably Areiiig belt along 
the Highland border. Whether or not these granitic protrusions were 
’ I suggested tliis jiossible comieetioii many years ago in Trails. Geol. Soc. Edin. vol. ii. (1874) 
p. 21. 
2 The volcanic geology of the Cheviot Hills is described by Mr. Teall, Geol. Mag. for 1883, p. 
106 ; and by Mr. Clongh, Mum. Geol. Survey, “Geology of the Cheviot Hills,” Sheet 108 N.E., 
1888, p. 24. 
3 See the descriptions of the Shap granite by Messrs. Marr and Harker, Quart. Journ. Geol. 
Soc. xlvii. (1891) p. 266, and xlix. (1893) p. 359. 
