Caps (see Polar Caps).
Carbon dioxide, [39], [161], [164-168].
Carbonic era of Earth, [134], [141], [142].
Carets, [265-270];
natural formations, [231], [232];
form and position of, [266], [267];
reason for shape of, [268];
associated with canals, [267], [269];
help in solution of riddle, [270];
act like oases, [333].