460 
THE CARBONIFEROUS VOLCANOES 
BOOK VI 
Carboniferous formations. The area between Edinburgh and Linlithgow 
and the hills of the north of Fife furnish many examples. 
Jhe connection between bosses and intrusive sheets is instructively 
exhibited in a railway cutting to the west of Edinburgh, where the section 
shown in Fig. 1G7 may lie seen. In the space of a few yards no fewer 
than four distinct bands of diabase traverse the shale, thickening rapidly 
in one direction and uniting with a large boss of more coarsely crystalline 
material. Such connections must exist in all sills, for tlie materiafinjected 
as a sheet between stratified formations cannot but be united to some column, 
dyke or irregular protrusion which descends to the parent magma in the 
interior. But it is very rarely that the geologist is permitted to see them. 
Dykes take a comparatively unimportant place in the eruptive 
phenomena of the puys. They occur in some ■ numbers, but on a small 
scale, among the tuff vents, and there they can without much hesitation be 
Eio. 169. Dyke rising tlirougli the Hurlet Limestone and its overlying sliale.s. 
Quarry, Linlitligow.shire. 
Silvennine 
set down as part of the phenomena of eruption through these pipes. The 
Binn of Burntisland, which has been so often referred to in this Chapter, 
may again be cited as a tj^iical vent for the display of this series of dykes 
(Figs. 149 and 159). Two additional illustrations from this locality are 
