472 
THE CARBONIFEROUS VOLCANOES 
BOOK Vi 
Owing to a cliango in tlie direction of strike the rocks now wheel round and for 
a time run nearly parallel with the coast-line, while they are partly concealed by 
blown sand and herbage. The shales and limestones just mentioned are not coii- 
stant, and are soon lost, but about a (juarter of a mile westward a band of tuff begins 
on the .same horizon or near it, and increase.s in thickness towards the west, wdiere 
it i.s associated with other sediments. The shore ceases to furnish a continuou.s 
section, so that recourse must be had to the craggy slopes immediately to the north, 
where the rocks can be examined on a cliff face (Fig. i 53). There the tuff just re- 
ferred to, together with some oveilying bands of sandstone, is seen to pass under the 
group of basalts last enumerated. It is a green, stratified rock, perhaps 60 feet thick 
at Its ma.\imum, but dying out rapidly to north-west and south-east. It encloses balls 
ol basalt and subangular and rounded fragments of sandstone, limestone and shale. 
A mass of coarse volcanic agglomerate which is connected with it and cuts across 
the ends of some of the basalts below, probably marks the position of the vent from 
which the tuff was ejected (Fig. 152). 
1 6. Black and grey shales forming a thin baud at the summit of King Alexander’s Cracr. 
15. Basalt, dark compact rock, wdtli an upper and lower highly scoriaceous and amygda- 
loidal band, 1 5 feet. 
14. Black shales, tufaceous green shales, sandstone, and 6 inches of coal, forming a 
group of strata about 12 feet thick between two ba.salts ; plants and cyprids 
abundant. (The coal .seam is .show'n in Fig. 151.) 
13. Basalt, dull, earthy and highly amygdaloidal, with abundant calcite in kernels and 
veins about 1 5 feet, but varying in thickness. 
12. Basalt, forming a well-marked bed from 12 to 25 feet thick. It is a compact black 
olivme-bearing rock, sparingly amygdaloidal, but showing the usual dull green, 
earthy scoriforin base. The upper surface is singularly irregular, having, in flow- 
ing, broken up into large clinker-like blocks, which are involved in the immediately 
overlying basalt. The bottom also is very uneven, for the basalt has in some places 
cut out the underlying shales, so as to rest directly upon the basalt below. 
1 1. Black shale, varying up to 6 inches, but sometimes entirely removed by the overlyino' 
lava-stream. 
10. Basalt, containing large irregularly spheroidal masses of hard black finely vesicular 
material enclosed in more eartliy and coarsely vesicular rock. The vesicles are 
sometimes elongated parallel to the bedding, but have often l.een drawn out round 
a spheroid ; some of them measure nearly a foot in length by 2 or 3 inches in 
breadth. The* upper surface is uneven and coarsely amygdaloidal. 
9. Basalt, hard black, with abundant olivine, and a columnar structure. 
8. Green shale, 6 inches to 1 foot, much liaked and involved in the overlying basalt. 
/. Basalt, dull-green, earthy, amygdaloidal, varying from 10 to 40 feet in thickness. 
6. Blue shale, disapiiearing wdiere the basalt above it unites with that below. 
5. Basalt with olivine, forming a thick irregular bed, wdiich in some places is black and 
compact, in others green, earthy and amygdaloidal. The upper iiart is particularly 
cellular. 
4. Sandstones forming a thick group of beds wdiich have long been quarried for building- 
stone at the Grange and elsewdiere. 
3. Black shales. 
2. Limestone (Bdrdiishocse). 
1. Sandstones, shales and thin limestones forming the strata at Burntisland through 
which the sills of that district have been injected (Fig. 159). 
Uie phenomena of sills are almndantly developed among the Carbon- 
iferous rocks of the basin of the Firth of Forth, and some of the more 
remarkalile e.xamples in this district have been already cited. Taking now 
a general survey of this part of the volcanic history, I may observe that if 
the sills are for a moment considered siiujily as they appear at the surface, 
