52 
ST. HELENA. 
which, in the course of future events, became the prison of one of 
Europe’s greatest monarchs. 
Repeated outpourings of lava would in time raise the crater-edge 
above the surface of the water, and the flow of lava inclining from 
it would eventually bring up the land to the same elevation. At an 
early period the crater would doubtless have its edge intact, and would 
necessarily contain water, which, during the interval between 
volcanic action, would mis with bits of broken rock, debris, and 
dust rolling down into it from the disintegration of its sides, and 
produce volcanic mud. A renewal of volcanic activity would first 
of all discharge from the crater this mud, accompanied with steam 
and water ; the rubble, or small fragments of rock, which, being 
heaviest, would sink to the bottom, would next be shot forth, and 
finally the molten lava would follow, thrown up high into the air 
amidst smoke, dust, and heavy clouds, just as in the present day we 
witness it at Vesuvius ; sometimes so high that detached fragments 
of lava, rendered spherical by their passage through the air, would 
descend in the form of bombs weighing half a ton or more. The 
lava would, for the most part, however, descend in huge sheets of 
liquid matter. A period of quiescence, or rest from volcanic dis- 
charge, extending over a century or two," would then intervene, 
when another similar outpour would follow : first mud, then 
rubble, followed by the pure lava, and this would, with in- 
tervals of rest, be repeated through hundreds of centuries until 
the edge of the great crater was built up to thousands of feet in 
height, with the land on its outer sides, excepting that towards 
which the prevailing wind blows, sloping outwards at such angles 
as the flow of lava naturally takes, probably 5° or 7°. Now this is 
precisely what we find on examining that part of St. Helena 
which is outside of the crater-walls. The whole of this portion of the 
Island is thus built up of numerous layers of mud, rubble, and lava ; 
occasionally the former two are missing in the regular order, and 
beds of lava overlie beds of lava, but such is the exception ; and 
although it is difficult now, in consequence of disintegration and 
surface-soil overlying them, to trace the distinct strata, it is easy to 
count, on the northern face of the Island, at least forty or fifty 
# C. Piazzi Smith states, with reference to Teneriffe, that volcanic outbursts occur once in 
a century. 
