oral reefs, 153, 353.

Corona, realm of the, 73.

Craters. See under VOLCANOES.

Crevasse, a barrier to the explorer, 218.

Crevice water, 250.

Curds, 214.

Currents,
coral reefs in Florida affecting the velocity of, 153;
equatorial, 150;
of the Gulf Stream, 147-149;
hot and cold, of the sea, 102;
ocean, 145;
oceanic action of trade winds on, 145;
effect on migration of, 157;
icebergs indicating, 243;
surface, history of, 172;
uprushing, near the equator, 106.

Cyclones, 111;
cause of, 111;
of North America, 111;
secondary storms of, 112.

Deltas, 173, 187.

Deposits, vein, 260, 261.

Deserts, interior, 158.

Dew, 159, 160;
a concomitant of cloudless skies, 160,
and vegetation, 160;
formation of, 159-161.

Diablerets, 174.

Diagram of a vein, 260;
showing development of swamp, 335;
how a portion of the earth's surface may be sunk by faulting, 374;
growth of mangroves, 340;
the effect of the position of the fulcrum point
in the movement of the land masses, 94.

Diameter of our sphere at the equator, 62;
of the earth, 82.

Dikes, 192, 293; 305-310;
abounding in volcanic cones, 305;
cutting through coal, 306;
driven upward, 307;
formation of, 305, 310;
material of, 307, 308;
representing movements of softened rock, 309;
their relation to volcanic cones, 307;
variations of the materials of, 307, 308;
waterfalls produced by, 192;
zone of, 306.

Dismal Swamp, 95, 333.

Distances,
general idea of, 27;
good way to study, 27, 28;
training soldiers to measure, 28.

Doldrums, 104, 109;
doldrum of the equator, 109;
of the hurricane, 109.

Drainage, imperfect, of a country affected by glaciers, 242.

Dunes, 123, 124, 325, 326, 387;
moulded, 387.

Duration of geological time, 389.

Dust accumulations from wind, in China, 122.

Earth,
a flattened sphere, 82;
air envelope of the, 98;
amount of heat falling from the sun on the, 41;
antiquity of the, 391;
atmosphere of the, 98;
attracting power of the, 127;
axis of the rotation of the, 58;
composition of the atmosphere of the, 98;
crust of the, affecte