Magnetism, of minerals, [451].

Magnetite, [452].

Malachite, [453].

Mamelons, [105].

Mammoth Cave, [182], [183].

Mantle, rock, [155].

Map, contour, nature of, [467];

of Armorican mountains, [438];

of barrier beaches, [242-243];

of bowlder train from Iron Hill, [306];