26 
TH& CARBONIFEROUS VOLCANOES 
BOOK VI 
in ,m f y s “‘ «• kid “»™ 
lithological characters The dark 1 ^ lnferre<i from their general 
points to the Drobihlp h t - d r carkonaceous as P e et of the limestones 
remains of the calcareous Tr™'" m " ° r 3t ^ Ch decayed ve g e tation with the 
calcareous organisms of which these strata chiefly consist. 
The thin unimportant bands or partings 
ol dark shale show that only the finest 
muddy sediment reached the quiet depths 
in which the strata were deposited, while 
Fig. 186.— -Section of intercalated dark lime- 
stone, shale ami chert in the tuff south of 
Foyll Vaaish Bay, Isle of Man. 
1. Limestones and shales ; 2. Chert ; 3. Tuff, 
vvii 
the macerated fern-fragments suggest 
long flotation and ultimate entombment 
of terrestrial vegetation borne seawards 
irom some neighbouring land. 
The cherty bands and nodules, like 
the flints of the chalk, bear their testi- 
mony to the quiet character of the sedi- 
mentation in rather deepwater beyond the 
land was mainly accumulated on the Staton” - “fT** from 11,8 
parte of the series of deposits ClXo m ^ °'T thaB siIic “™ 
they are to be referred tn nZ ^ lnvestl g ated - Whether or not 
cherts of the Lower SilurhanT f ° aU8e ® lke chaIk -flmt S , and the radiolarian 
remarkable JS'„n - •>» 
which has now been observed in . , . th Tolcame phenomena, 
world. ian T wl(iel T separated areas all over the 
evidL^dlturbed ^ ™ <***> ***« 
^Inf^Z V ttZ e ZpZ th a°i h p^rt 
tuffs, indeed, there is on the wh i " Trough out the series of 
gest ve of s tong cuCts .**«“ ° f “V «nW«. aug- 
ment of the vo'enl de it™ ZZ ‘I th » di V'“l and reassort- 
such a way as to lib„ , T , “ d Stm “’ weK discharged in 
hollows. There does not seeirfl V "' i' ^ aea " floor illto ridges and 
bottom water to love C, Zee a ™ to" ”’ ovem “ t “ the 
‘hey remained longenongh to a „w Zf‘T f "*“> ** ™ “ ‘hat 
siliceous ooze to gather in tlw ! L .a" more of “leareous and 
stood uneffaced until hnried 1 , ? V ' W 11 e tke intervening ridges still 
some transient « or !' ' leit f ^ 
spread out the volcanic detritus hi f ve , leaclle d the bottom and 
of the still water are not im f *n ‘" UC 1 exce Pti° na l disturbances 
stratification, and even by diSncf ft I ^ ° Ccasional w ell-defined 
tuff. 7 dlStlllCt Talse-hedding, m certain finer layers of 
The materials of the tuff, are remarkably uniform in character and 
