GEOLOGY AND MINERALOGY. 73 
New Ground, Horse Pasture, and other portions of the Island, sloped 
gently down to the sea without intervening precipices, there doubtless 
existed long, low-lying coasts, upon which accumulated a white sand 
of broken shells, finer in grain but not unlike that now found at 
Ascension. This sand, having drifted into secluded places, and 
becoming compressed and hardened, now appears in the form of lime- 
stone beds, fragments of which occur at Lot’s Wife Ponds, Bankses 
Bidge, and Bupert’s Beach. These beds vary very greatly now in 
altitude, some being on a level with the sea, others as much as 
four or five hundred feet above it. They contain embedded 
fragments of very old looking lava rock, and are inclined inland, as 
at Lot’s Wife, at an angle of 20°, but whether this inclination is due 
to drift or slight upheaval it is difficult to determine. The strati- 
fication of the beds, however, rather indicates the latter. The hardest 
of this limestone, when burnt, yields an excellent building mortar, 
but it exists in small quantities. 
In many respects there exists evidence of the great mass of the 
Island having cooled slowly. It is indicated by the entire absence of 
obsidian, as well as by the vitreous edges of the dikes. The hot matter 
"winch formed the dike, coming into contact with tbe cold sides of 
the opening which it filled, would quickly cool and account for the 
glass-like edges, in some places passing into serpentine, which occur 
in many of the dikes at St. Helena. 
Earthquakes happen so rarely, and when they do are so slight, 
that they scarcely need be noticed as occurring at all. Four only 
have been recorded during the last 370 years — viz., one on the 15th 
June, 1756; another in 1780; one on the 21st September, 1817; 
and the last on the 15th July, 1864. 
It is not a little remarkable that in so complete a volcanic formation 
no traces of sulphur occur, either native or in combination with 
other substances ; and of the numerous springs of water which exist 
only some few appear impure, and that caused only by the presence 
oi sea salt, which is plentiful in some of the higher beds of laterite 
and rubble. Not a single instance of a spring above the ordinary 
temperature is found, and, indeed, no recent signs whatever exist 
anywhere to indicate proximity to a volcanic locality.* 
, Helena Monthly Register lor 1S10 states that “ a warm mineral spring was a 
s ort time ago discovered near Longwood. It rises from under an immense body of sofid rock, 
51 temperature is 60° Fakr. which was 6 ° above the temperature of the surrounding atmo- 
