第78章

Glaciers, their structure.

Glossiness of texture, origin of.

Gneiss, derived from clay-slate.

-with a great embedded fragment.

Gneiss-granite, form of hills of.

Good Hope, Cape of.

Gorges, narrow, at St.Helena.

Granite, junction with clay-slate, at the Cape of Good Hope.

Granitic ejected fragments.

Gravity, specific, of lavas.

Gypsum, at Ascension.

-in volcanic strata at St.Helena.

-on surface of the ground at ditto.

Hall, Sir J., on the expulsion of carbonic acid gas.

Heat, action of, on calcareous matter.

Hennah, Mr., on ashes at Ascension.

Henslow, Prof., on chalcedony.

Hoffmann, on decomposed trachyte.

Holland, Dr., on Iceland.

Horner, Mr., on a calcareo-animal substance.

-on fusibility of feldspar.

Hubbard, Dr., on dikes.

Humboldt on ejected fragments.

-on obsidian formations.

-on parapets round craters.

-on sphaerulites.

Hutton on amygdaloids.

Hyalite in decomposed trachyte.

Iceland, stratification of the circumferential hills.

Islands, volcanic, distribution of.

-their elevation.

Incrustation, on St.Paul's rocks.

Incrustations, calcareous, at Ascension.

Jago, St.

James island.

Jasper, origin of.

Jonnes, M.Moreau de, on craters affected by wind.

Juan Fernandez.

Keilhau, M., on granite.

Kicker Rock.

King George's sound.

Labrador feldspar, ejected.

Lakes at bases of volcanoes.

Lamination of volcanic rocks.

Land-shells, extinct, at St.Helena.

Lanzarote, calcareous beds of.

Lava, adhesion to sides of a gorge.

-feldspathic.

-with cells semi-amygdaloidal.

Lavas, specific gravity of.

Lava-streams blending together at St.Jago.

-composition of surface of.

-differences in the state of their surfaces.

-extreme thinness of.

-heaved up into hillocks at the Galapagos archipelago.

-their fluidity.

-with irregular hummocks at Ascension.

Lead, separation from silver.

Lesson, M., on craters at Ascension.

Leucite.

Lime, sulphate of, at Ascension.

Lonsdale, Mr., on fossil-corals from Van Diemen's land.

Lot, St.Helena.

Lyell, Mr., on craters of elevation.

-on embedded turtles' eggs.

-on glossy coating to dikes.

Macaulay, Dr., on calcareous casts at Madeira.

MacCulloch, Dr., on an amygdaloid.

-on chlorophaeite.

-on laminated pitchstone.

Mackenzie, Sir G., on cavernous lava-streams.

-on glossy coatings to dikes.

-on obsidian streams.

-on stratification in Iceland.

Madeira, calcareous casts at.

"Magazine, Nautical," account of volcanic phenomena in the Atlantic.

Marekanite.

Mauritius, crater of elevation of.

Mica, in rounded nodules.

-origin in metamorphic slate.

-radiating form of.

Miller, Prof., on ejected Labrador feldspar.

-on quartz crystals in obsidian beds.

Mitchell, Sir T., on bombs.

-on the Australian valleys.

Mud streams at the Galapagos archipelago.

Narborough island.

Nelson, Lieut., on the Bermuda islands.

New Caledonia.

New Red sandstone, cross cleavage of.

New South Wales.

New Zealand.

Nulliporae (fossil), resembling concretions.

Obsidian, absent at the Galapagos archipelago.

-bombs of.

-composition and origin of.

-crystals of feldspar sink in.

-its irruption from lofty craters.

-passage of beds into.

-specific gravity of.

-streams of.

Olivine decomposed at St.Jago.

-at Van Diemen's land.

-in the lavas at the Galapagos archipelago.

Oolitic structure of recent calcareous beds at St.Helena.

Otaheite.

Oysters, extinction of.

Panza islands, laminated trachyte of.