[479] They have been recognized and mapped by Mr. B. N. Peach for the Geological Survey. See Sheets 11 and 17, Geol. Surv. Scotland.
Fig. 174.—Section showing the connection of the two volcanic bands in Liddesdale.
1. Upper Silurian strata; 2. Upper Old Red Sandstone; 3. The lavas of the Solway plateau; 4. Agglomerate neck with lava plug, belonging to the plateau system; 5. Calciferous Sandstone series; 6. Thick Carboniferous Limestones; 7. Tuff, and 8. Lavas, of the upper volcanic band, connected with the puys; 9. Agglomerate neck with lava plug belonging to the puy-system; 10. Basic sill.
Fig. 175.—Diagram to show the position of a mass of Upper Old Red Sandstone which has fallen into the great vent near Tudhope Hill, east of Mosspaul.
1. Upper Silurian strata; 2. Outlier of Upper Old Red Sandstone; 2´. Large mass of this formation in the vent; 3. Agglomerate of the neck with andesite intrusion (4).
The materials ejected from the Liddesdale vents include both basaltic lavas and tuffs. The former are sometimes highly vesicular, especially along the upper parts of the flows. They are thickest towards the north, and in Windburgh Hill attain a depth of at least 300 or 400 feet. In that part of the district they form the lower and main part of the volcanic series, being there covered by a group of tuffs. But a few miles southwards, not far to the west of Kershopefoot, they die out. The tuffs then form the whole of the volcanic band which, intercalated in a well-marked group of limestones, can be followed across the moors for some six miles into the valley of the Esk, where an interesting section of them and of the associated limestone and shales is exposed ([Fig. 174]). At Kershopefoot, a higher band of basic lava overlies the Kershopefoot limestone, and can be traced in scattered patches both on the Scottish and English side of the Border.
END OF VOL. I.
Printed by R. & R. Clark, Limited, Edinburgh.
TO ACCOMPANY SIR ARCHIBALD GEIKIE'S "ANCIENT VOLCANOES OF BRITAIN"
Map IV.