lx PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
great mixture of contemporaneous igneous and common detrital pro- 
ducts in Cumberland and Wales having extended also to Ireland, and 
that there was at this time a great upburst of igneous matter, fluid 
molten rock rising through fissures and cracks amid the older accu- 
mulations, while ashes and lapilli were vomited forth from voleanic 
vents, partly perhaps im the sea, and partly into the atmosphere, 
where they were borne about in mechanical suspension, as ashes now 
frequently are for distances of many hundred miles, until finally they 
fell upon sea or dry land as the case might be. 
When we read the descriptions of voleanic eruptions, such as that 
of Tomboro, in Sumbawa, given by Sir Stamford Raffles, the explo- 
sions durimg which were heard so loud at Macasar, 217 nautical miles 
from Tomboro, that, considering there was an engagement with pirates 
somewhere in the neighbourhood, a cruiser, with troops, was des- 
patched to look after them, these explosions also reported to have 
been distinctly heard at Ternate, 720 nautical miles distant,—miles 
around the voleano darkened by the ashes thrown into the atmo- 
sphere and falling in all directions,—we need not refer to larger vol- 
canic eruptions, long continued, than now occur, for the origin of the 
mixed matter formimg these great accumulations. When we hear 
of a darkness from the ashes thrown into the atmosphere, con- 
tinued many hours, and so great that it was equal to the darkest night, 
that the seas around the island were covered with pumice and ashes, 
that the waters were greatly agitated by earthquake waves, and that 
the ashes which fell so far off as Bima broke in the Resident’s 
house in several places, we see causes and their effects well-suited in 
our own days to produce deposits similar to those which seem to 
have required physical agencies of a like kmd over the area now occu- 
pied by the British Islands at this old geological epoch. 
We have to look back to a time, after a thick accumulation of 
matter now forming the Skiddaw slates, the lower dark slates of 
North Wales, with their cappmg of variegated beds, and of sand- 
stones and conglomerates, and the continuation of these beds, va- 
riously modified, into Ireland, when volcanic forces burst out furiously, 
scattering ashes around, so that fallmg mto waters, they formed the 
parts, or the whole of beds, or were eiecceeiecd with commen de- 
trital accumulations, according to circumstances. That there were 
times of repose, durmg even the accumulations of the ash beds, is 
evidenced by the occurrence of organic remains in them, just as we 
find these remains entombed amid the deposits of ordinary mud or 
silt. They occur in a manner whence we infer the existence of life 
upon the ashes as upon any ordinary bottom, and as many a molluse 
and other marine creature must live at the present day in seas adjoin- 
ing volcanic districts and islands. ‘This volcanic condition of the area, 
productive of such marked results, m the end ceased, at least over 
part of it, and was succeeded by a geological time when the voleanic 
products became covered for a long period by ordmary mud, sands 
and gravel, mingled at times with calcareous matter, here and 
. there, perhaps, some igneous action continuing, and producing its 
effects. So much of the accumulations of this geological time have 
