
816. The American Naturalist. [September, 
degree of metamorphism. The belt is penetrated by various kinds of 
igneous rocks; and the petrography and chemistry of rocks and 
minerals in every stage of metamorphism, induced by pressure and 
heat, can be traced out and its history deciphered to its minutest de- 
tails. It is rare to find rocks of known geological age in which such 
favorable conditions exist. ‘The histories thus elaborated can be used 
most advantageously in deciphering other localities whose history is 
written in less legible characters. 
Elevated Sea-Beach on Grand Cayman.—Southeast from 
the Isle of Pines, and distant about two and one-half degrees, lies 
the Grand Cayman Island. Politically it is a dependenty of 
Jamaica, from which it is separated about as far as it is from the 
Isle of Pines. - Geographically it seems to be more closely associated 
with Cuba than with Jamaica, in so far as any argument derived - 
from the ocean depths around would indicate. The water. gradu- 
ally deepens from about three hundred and fifty fathoms at Cape Cruz 
(Cuba) to about eight hundred at Cayman Brac and Little Cayman; 
thence to over one thousand one hundred fathoms as one approaches 
the Grand Cayman. The course from Cape Cruz to the Grand 
Cayman is west by south. The distance is one hundred and forty 
nautical miles; and as the smaller islands of Cayman Brac and 
Little Cayman lie almost in the line indicated between Cape Cruz 
and Grand Cayman, and asthe water deepens north and south of the 
line, one readily recognizes the presence of a submarine ridge stretch- 
ing from Cuba to Grand Cayman, of which =r Caymans are them- 
selves merely coral-capped summits. 
The main fact here indicated is the distance, and the depth of ocean 
which surrounds this island of the Grand Cayman ; to the south of it 
two, and even three, thousand fathoms are found. - During the past: 
winter I made a brief visit to the southern shore of the Grand Cay- 
man. My attention was called to a sea-beach or wall, fifteen feet above 
the present tide-level. The most casual observer could not fail to 
notice that it indicated the action of the water, and that the materials 
of the beach came from the water. The broken and worn masses o 
coral along this higher shore led to but one conclusion. I immediately 
began speculating on the time required to form that shore-line, and how 
long it took place, etc. The fact is, however, that the whole thing 
happened in a single day, during one of the fearful hurricanes which 
swept over the island in the earlier part of thiscentury. The testimony 
on this point is quite too direct and positive to admit of any doubt. 




