68 
ST. HELENA. 
iii doing so, prejudices must disappear, and that scientific investiga- 
tion only helps us the better to understand revealed Scripture. 
Without taking into consideration the period occupied in building 
up the Island, the data we have to guide us in fixing its birth so long 
ago are those changes which have manifestly occurred in the contour 
of the land. If then we are able to fix definitely the outline of the 
formation as it originally stood, and then assume, after careful ob- 
servation, a rate for its disintegration and decomposition, we may 
easily arrive, by a simple calculation, at a fairly correct estimate of 
the time required for it to assume its present size and shape. If we 
pick up a piece of stone anywhere on the higher land and break it 
across, we see directly that its interior presents a hard bright metallic 
lava fracture very different in colour and texture from its external 
coating, which for about a quarter of an inch in thickness is soft 
and friable. We quite fail, indeed, to recognise the inside and the 
outside of the stone as the same substance ; but it is only exposure 
to wet and dry weather alternately that has thus oxydized or rotted 
and changed the external surface, which crumbling away and falling 
into clay or dust allows the atmospheric influence to continue acting 
on the stone, eating deeper and deeper into it until it becomes, in 
time, completely reduced to powder. This process is continually 
going on in large rocks as well as small stones, and the higher the 
altitude, where the most moisture exists, or the nearer the rocks 
are to the influence of the sea, so much quicker does disintegra- 
tion and decomposition take place. There remains no landmark 
whereby to judge how much higher the edge of the great crater, or 
central mountain ridge, once was than it is at present, but that it 
was much higher is certain. Its lava edges have through ages (just 
as is still the case, with the assistance also of vegetation), gone on 
passing into alluvial soil, which in its turn has been washed down by 
rains to the valleys and plateaux of the lower districts. Much of the 
upper surface of the Island has in this way been removed, while much 
also still remains as marl in a transition state from lava rock to 
surface soil ; indeed most of the upper parts of the Island are now 
covered with these grey, blue, or yellow marls, but they do not 
extend to more than a few feet in depth, when the hard lava again 
occurs. There are many opportunities of observing this in the road- 
side pits which the road-menders, searching for material, have opened. 
The rapidity with which rocks disintegrate or wear away varies 
