476 
THE CARBONIFEROUS VOLCANOES 
BOOK VI 
geologist with wonder to meet wdth those stumps of old volcanoes far to the 
west among the Silurian lowlands, sometimes fully ten miles away from the 
nearest relic of the bedded lavas connected with themd That these vents, 
though tliey rose through ground which at the time of their activity was 
covered with the volcanic series of the plateaux, do not belong to that series, 
birt are of younger date, has been proved in several cases by Mr. Peach. 
Fig. 174. — Section showing the connection of the two volcanic bands in Liddesdale. 
l. Upper .Silurian strata; 2. Upper Old Red Sandstone; 3. The lavas of the Solway i>Iateau; 4. Agglomerate 
iieck with lava plug, belonging to the plateau system ; 5. Calciferous Sandstone series ; 0. Thick Carbon- 
imrous Limestones ; 7. Tuff, and 8. Lavas, of the upper volcanic band, connected witli the puys ; 9. Ag- 
glomerate neck with lava plug belonging to the pny-system ; 10. Basic sill. 
He has found that among the blocks composing their agglomerates, pieces 
ot the sandstones, fossiliferons limestones and shales of the Cement-stone 
group, overlying the plateau-lavas, are to be recognized. These vents were 
tlierefore drilled through some part at least of the Calciferous Sandstones, 
wdiich are thus shown to have extended across the tract dotted with vents. 
After the volcanic activity ceased, fragments of these strata tumbled down 
from tlie sides into the funnels. Denudation has since stripped off the 
Calciferous Sandstones, hut the pieces detached from tliem, and sealed up at 
Fig. 175. — Diagram to show the po.?ition of a ma.s,s of Upper Old Bed Sand.stone which has fallen into 
the great vent near Tudhope Hill, east of Mosspaul. 
1. Upper Silurian strata ; 3. Outlier of Upper Old Red Sandstone ; 2'. Large mass of this formation in tlie vent ; 
3. Agglomerate of the neck ivith andesite intrusion (4). 
a lower level in the agglomerates, still remain. Mr. Peach’s observations 
indicate to how considerable an extent sagging of the walls of these orifices 
took place, with the precipitation not merely of blocks, hut of enormous 
masses of rock, into the volcanic chiimieys. In one instance, between 
Tndliope Hill and Anton Heights, a long neck, or perhap.s group of necks, 
which crosses the watershed, .shows a mass of the red sandstone many acres 
in extent, and large enough to he inserted on the one-inch map, which has 
fallen into the vent (Pig. 175). 
The materials ejected from the Liddesdale vents include both basaltic 
lavas and tuffs. Tlie former are sometimes highly vesicular, especially 
’ They liave been recognized and mapped by Mr. ]i. S'. Peach for the Geological Survey. See 
Sheets 11 and 17, Geol. Swfv. Hcotlmul. 
