72 
ST. HELENA. 
rently unchanged, and though occasionally slices of cliff do fall 
away, such instances are rare, at long intervals, and scarcely ever 
known by any one person to happen at the same spot. At the 
present time progressive rates of three inches and one inch per 
year are certainly too great, but we may fairly take such an average, 
because the horizontal advance of the sea would lessen each year as 
the vertical depth of the cliff to be removed increased. 
The Island is now bounded by a coast line of 30 miles. Its super- 
ficial area measures 45 square miles, or 28,800 acres. A careful 
calculation estimates the entire encroachment of the sea at 30 square 
miles, or 92,928,000 square yards, while no less than ll,587,2S0,00O 
cubic yards ot solid land have been removed through its denuding 
power. How assuming, from our previous calculation, the Island to 
have existed only 40,000 years, we have an annual encroachment of 
the sea on the land of 2323 square yards, and a yearly removal by 
denudation of the enormous mass of 289,082 cubic yards. The 
numerous dikes which jut out around the windward coast from 
Turk’s Cap to Man and Horse show this action of the sea, es- 
pecially at a place called “.Lot’s Wife Ponds,” where a fine illustra- 
tion ot this terribly destructive agency is seen in the ruins of many 
dikes, which the devastating power of the waves has brought down 
to their own level. They have all the appearance of regularly built 
jetties running out through the surf into the sea. It would be difficult, 
however, to land at the spot, as they cross each other and lie in 
almost every direction just below the surface of the water. A portion 
of one of the hardest, a very dense block of black basaltic rock, has 
long defied the force of the water, and stands in a striking position, 
about twenty feet away from the mainland. It measures about fifty 
feet in height, thirty in width, and from four to six in depth, and 
from its remarkable appearance bears the name of “ The Chimney.” 
Several small islets, some of which stand sufficiently away from 
the coast to allow a ship of large size to pass between, also testify to 
this destructive action of the sea. Both Egg Island and George’s 
Island show the same formation of lava beds as the adjacent coast, 
while Speery Island marks a portion of the great Lot dike, and 
Peaked, or Lanark, Island is a curious remnant of a scoriaceous mass 
of cinders firmly cemented together, the counterpart of which is seen 
in a thick bed of rubbish on the mainland opposite. 
At a time when the plains of Rupert’s' Hill, Half-tree Hollow, 
