NOTES ON EAETHQUAKES. 
207 
direct evidence of volcanic action in the British Isles an inte- 
resting question. There is geological proof that in the earlier 
ages of the planet's history Great Britain possessed her active 
volcanos, and must have been shaken by earthquakes of terrible 
potency. 
When the rocks that constitute the mass of Snowdon were 
being deposited in the seas of the Lower Silurian epoch there 
must have been an active volcano near at hand, for there we 
have marine deposits, full of the remains of animals which 
lived in the Llandeilo and Caradoc periods, inter stratified with 
felspathic ashes, traps, and porphyries which no doubt were 
erupted from a volcano into the air, and then fell and sank 
through the waves. 
Every geologist who visits Edinburgh must be struck with 
the evidences of volcanic action, which must have been rife in 
that district during the Carboniferous period, and volcanic 
action combined with the stratifying operations of sea-waves 
and currents. 
Limestone of the age of the Lias has been converted by a 
Plutonic rock into crystalline marble in the Isle of Skye ; and 
the basaltic columns of the Giant's Causeway in Ireland, and 
the Isle of Staffa, are currents of lava which are of later 
date than the chalk, and probably were contemporaneous with 
some of the lavas of Central France and the Bhine. 
There are two curious notices, brought forward by Dr. 
Thomas Wright, in the Miscellanea of the Athenceum of 
November 28th, respecting instances of recent volcanic action 
in the British Isles. He informs us that Adam de Marisco, a 
friend of Simon de Montfort, and an English scholar of the 
thirteenth century, has recorded a volcanic eruption in the 
Channel Islands as occurring in his time (about the middle of 
that century) ; and also that the “Annual Register" for 1773 
contains a notice of the eruption of “ liquid fire " and “ vast 
bodies of combustible matter " from Moel Famma, a hill on 
the borders of North Wales, on the 31st of January of the 
same year. These records are probably more singular than 
true ; for in the case of Moel Famma no volcanic rock of any 
kind is marked by the geological surveyors on the hill, or in 
the district, and it is extremely unlikely that these accurate 
observers would have passed by relics of the “ liquid fire." 
Some geologists have argued that the phenomenon of vol- 
canic action was far more developed in the early ages of the 
earth's history than at present, but further investigations into 
the philosophy of the subject throw more than a doubt on the 
truth of this theory. This constant earthquake and volcanic 
doctrine was invented to account for the earth tempests and 
continual blowing up of the earth's crust, which were supposed 
p 2 
