rounded and angular fragments of igneous rock lying in a brown, rather ferruginous paste, that looks like the débris of a basaltic , rock.
Fig. 12.
Coxe's Rough, Basalt Quarry.
If these beds be connected with the basalt, which seems almost certain, it shows that the basalt was an eruptive[1] rock, poured out at the surface in the form of a sheet of lava, whether subaqueous or subaerial, immediately after the formation of the part of the Coal-measures which lie below it. These trappean breccias or conglomerates belong to and pass into the Coal-measures, and therefore the basalt of the Rowley Hills also belongs to and forms part and parcel of the Coal-measure series. That it was formed during the Coal-measure period seems also to be probable, from the fact that it has been subsequently affected by all the dislocations and other accidents that have happened to the Coal-measures.
The Netherton tunnel has lately been driven right through the base of the ridge between Oakham and Farnley Hill, running from Tividale to near the Gads Green reservoir. Eight or nine shafts were sunk from the surface along the line of this tunnel down to its level, which is that of the canal at Tividale, or 484 feet above the sea. Neither in the tunnel nor in any of the shafts
- ↑ This term of "eruptive" is sometimes applied to granitic rocks, which, however intrusive they may have been, clearly cannot have been eruptive, that is, can never have burst out to the surface. I would, therefore, by an eruptive rock mean only such a rock as could have been ejected out of the earth and poured over its surface, whether that surface was there covered by air or by water.
