39 ° 
THE CARBONIFEROUS VOLCANOES 
BOOK VI 
thoiigh it is, does not represent the whole of the oiiginal area included 
within the range of the discharges of ash and stones, for much has been 
removed by denudation. During pauses of various length between the 
eruptions, waves and currents washed down the heaps of volcanic material 
and distributed ordinary sediment over the bottom of the water. Hence, 
abundantly interstratitied in some parts of the tuff, seams of sandstone, blue 
and green shale, cement-stone and limestone occur. One thick band of 
limestone may be traced from near Tynningham House to Whittinghaine, 
a distance of about four miles ; another patch appears near llockville House ; 
and a third at I’hodes, near North Berwick. No fossils have been noticed 
in these limestones. The calcareous matter, together sometimes wdth silica, 
appears to have been supplied, at least in part, by springs, which may have 
been connected with the volcanic phenomena of the district. The North 
Berwick limestone, in particular, has the peculiar carious wavy structure 
with minute mamillated interstices so common among sinters. It contains 
grains of pyrites, flakes of wdiite kaolin, which probably represent decayed 
prisnus or tufts of natrolite, and cavities lined with dog-tooth spar. Some 
portions give out a strongly foetid odour when freshly broken. 
After the tuff's of the Garleton plateau had accumulated to a depth of 
perhaps 200 feet or more, lavas began to be poured out. First came 
basic outflows (olivine - basalts with picrites) and andesites (porphyrites), 
which form a thin but continuous sheet all over the area. These were 
succeeded by the series of trachytes which distinguish this area. Although 
the observer remarks the absence there of the usual terraced arrangement, 
yet from some points of view, particularly from the westward, a suc- 
cession of low escarpments and longer dip-slopes can be detected among 
the trachytes of the Garleton Hills, while there can be no doubt that, in 
spite of their irregular lumpy contours, these lavas lie as a great cake above 
the lower platform of more basic flows (Fig. 10). There is evidence that 
during the emission of the trachytes occasional eruptions of andesite took place. 
Not the least striking and interesting feature of this plateau is the size and 
distribution of its necks, to which reference will be made in the sequel. 
The latest eruption in the Garleton area had ceased and the cones and 
lava sheets had probably been buried under sediment before the commence- 
ment of the deposition of the Hurlet or thick Main Limestone of the 
Carboniferous Limestone series which lies immediately to the west of the 
plateau. 
The tuffs of the plateaux are seldom fossiliferous, probably for the same 
reason that fossils are scarce in the Cement-stone group which the plateau 
volcanic rocks overspread and with which they are interstratified. Occa- 
sional stems and other fragments of vegetation occur in the jdateau-tufls, as 
in those of North Berwick, where I have found a decayed coniferous trunk 
three feet in length. Tlie green tuff at the base of the volcanic group of 
Arthur Seat contains abundant macerated plant - remains, together with 
scales of Bhizodus and other fishes. In some places the plants are repre- 
sented by trunks or roots, which appear to remain in their positions of 
