DEBRIS, a convenient term adopted from
the French for all heterogeneous ac-
cumulations of wasted material, 29.
Degradation (Lat. de, down, and gradus,
a step), the act of wearing or wasting
down gradually or step by step, 17.
Deinotherium (Gr. deinos, terrible, and
therion, wild beast), figured, page 164.
Delta, and deltoid, deposits described, 18.
Dendrerpeton (Gr. dendron, tree, and
erpeton, reptile), reptile of the coal
period, 95.

Denudation (Lat. de down, and nudus,
naked). The removal of superficial
matter, so as to lay bare the inferior
strata, is an act of denudation; so also
the removal by water of any formation
or part of formation.

Detritus (Lat. de, from, and tritus, rub-

bed), matter worn or rubbed off rocks
by aqueous or glacial action.

Devonian or Old Red Sandstone system,
80-86.

Dicynodon, triassic reptile, figured, 110.
Diluvial drift, Drift, or Boulder forma-
tion, 144.

Dip, or inclination, of strata, 31.
Diprotodon, figured, 147.

Dolomite, as a rock, 36; in permian
system, 104.

Dromatherium (Gr. dromaios, swift-run-

ning, and therion, wild beast), a mam-
mal of the triassic or permian period,
discovered in the red sandstones of
Carolina, North America, 110.
Dyke, wall-like masses of igneous matter
filling fissures in stratified rocks are so
termed, 33.

EARTHQUAKES, their effects as geological
agents, 26, 27, 163.

Encrinites, of silurian rocks, 76; of
mountain limestone, 96.

Eocene, or lower tertiary group, 136.
Eozoon Canadense, Laurentian fossil,
figured, 69.

Erosion (Lat. erosus, gnawed or worn
away), application of the term, 18.
Escarpment (Fr.), steep bluff edge or
precipice, 31.

Estuary deposits, nature of, 151.
Euomphalus (Gr. eu, well, and omphalos,

the navel), a coiled nautiloid shell of
the mountain limestone, 95.
Eurypterus (Gr. eurys, broad, and pteron,

a wing or fin), a genus of paleozoic
crustaceans, so called from their broad
thong-like swimming feet, 76, 83, 95.
Exuvia (Lat. exuere, to cast or throw off).
In zoology this term is applied to the
moulted or cast-off coverings of ani-
mals, such as the skin of the snake,
the crust of the crab, &c.; but in geo-
logy it has a wider sense, and is applied
to all fossil animal remains of whatever
description.

FABOIDEA, tertiary fruits, 140.

Fault, fissure or dislocation of strata, 33.

Fauna (Lat. fauna, rural deities), in geo-
logy, 67.

Favosites (Lat. favus, a honeycomb), a
silurian coral, 76.

Felspar (Ger. fels, rock, and spath, spar),
as a rock, 36; felspathic traps, 50.
Fens, or marine marshes, 154.
Ferruginous (Lat. ferrum, iron), impreg-
nated with iron; ferriferous, yielding
iron.

Fibrous texture, composed of fibres like
asbestos, 36.

Fire-clay of the coal-measures, 101.
Fishes, fossil, chief characteristics of,
and Agassiz's classification of, 84.
Fissile structure (Lat. fissus, capable of
being split), 39.

Flaggy, Flags, and Flagstones, are terms
applied to fissile rocks like paving-
stone, 34; Arbroath and Caithness
flagstones, 86.

Flexures, in stratification, 31.

Flint, as a rock, 36; formation of, in
chalk system, 133.

Flora (Lat. Flora, the goddess of flow-
ers), in botany, 67.

Fluviatile or river accumulations, post-
tertiary, 149.

Foliation, in metamorphic strata, 59.
Foraminifera (Lat. foramen, an opening),
a class of minute chambered shells,
with an orifice in the septa or plates
which separate the chambers, 21, 137,

160.

Forests, submerged, 155.
Formations, in geology, 8.

Fossils, fossil remains (fossus, dug up), 7.
Freshets or land-floods, their effects, 17.
Fuci, Fucoids, sea-weeds, or fucus-like

impressions in silurian rocks, 76; in
old red sandstone, 83; in oolitic, 120.
Fuller's earth, a variety of absorbent

clay, used in the scouring or fulling of
woollen cloth, 126, 133.

GANOID, Ganoidans, &c., a division of
fishes, 84.

Garnets, in metamorphic rocks, &c., 61.
Garnetiferous (fero, I bear), yielding or
containing garnets.

Gault (provincial), a member of the chalk
system, 126.

Gastornis, a gigantic bird of the lower
tertiary epoch, 140.

Geodes (Gr. geodes, earthy), a term ap-
plied to rounded pebbles having an
internal cavity lined with crystals;
also to rounded or nodular pebbles
themselves; and to nodules of clay or
ironstone, hollow within, or filled with
soft earthy ochre, 52.

Geology, object and scope of, 1, 2, 8;
theoretical, 9; practical, 10; how to
observe, 11.

Geysers, or hot springs of Iceland, 150.
Glacial phenomena of boulder-drift, 146,
147.

Glacier (Lat. glacies, ice), the term ap-
plied to those masses of ice which ac-

cumulate in the higher gorges and val-
leys of snow-covered mountains, 16.
Glossopteris, a fern of the oolite, 120;
permian, 106.

Gneiss, as distinguished from granite,
36; the gneiss group, 58-65.
Gold, principal repositories of, 79.
Granite, mineral composition of, 36, 46.
Granitic rocks, description of, 43, 45-48;
igneous or aqueous origin of, 45; where
found, 47; economic uses of, 48.
Graphite (Gr. grapho, I write), so called
from its use in making writing-pencils.
This substance consists almost entirely
of pure carbon with a small percentage
of iron, the proportions being about 90
to 9. It is also termed plumbago and
black-lead, from its appearance, though
lead does not at all enter into its com-
position.

Graptolites, characteristic silurian zoo-
phytes, 76.

Gravel, as distinguished from sand and
shingle, 36.

Greensand, a member of the chalk sys-
tem, 126.

Greenstones, varieties of, 50.

Greywackè (Gr. grau, grey, and wackè,
a mixed clayey rock), 66.
Grit, as distinguished from sandstone-
grindstone-grit, millstone-grit, 36.
Group, in geological classification, 40.
Gryphæa (Gr. gryps, a griffin), a beak-like
shell of the oolite, 121.

Gypsum (Gr. gypsos, from ge, earth, and
epso, I boil), originally applied to all
limestones, 36.

Gyracanthus, fish-spine, 95.

HAMITE, a chambered hook-shaped shell
of the chalk, 129.

Harlech grits, lower Cambrian, 70.
Heliolites (Gr. helios, the sun, and lithos),
silurian corals, 76.

Hitch, slip or displacement of strata, 33.
Holoptychius, a fish of the upper old red
and lower carboniferous ages, 85, 95.
Hornblende, as a mineral and rock, 36;
granitic rock, 46; metamorphic, 59.
Hymenocaris, Cambrian crustacean, fig-
ured, 71.

Hypersthene, as a mineral and rock. 36.
Hypozoic (Gr. hypo, under, and zoe, life),

as distinguished from azoic, 42, 57.

ICEBERG Gr. eis, ice, and berg, a moun-
tain), the name given to the mountain-
ous masses of ice often found floating
in the arctic and antarctic seas.
Iceland, volcanic discharges in, 164.
Ichnites, or fossil footprints, 110.
Ichthyolite, and ichthyodorulite, fish re-
mains, 85.

Igneous agency, its mode of operation
and results, 24-27.

Igneous rocks, nature of, 31; subdivi-

sions of, 43; relations to the stratified
rocks, 43.

Indurated, hardened by heat; and in

this sense should be kept distinct from
"hard" or "compact."

Infusorial accumulations, nature of, 21.
Ironstone, of the coal-measures, 101.

JET, as distinguished from ordinary coal,
36; in lias, 117.

Joints, divisional plains, "backs and
cutters," 94.

KAOLIN, a Chinese term for a fine pottery-
clay derived from the decomposition of
granitic or felspathic rocks, 48.
Keuper and Keuper marls, members of
the trias, 109.

Kimmeridge clay, Kimmeridge shale, or
"Kim coal," &c., 120.

LABRADOR rocks, upper Laurentian, 68.
Labyrinthodon, a batrachian reptile of
the new red sandstone, figured, 110.
Lacustrine or lake deposits, 152.
Laminated (Lat.), composed of thin plates
or lamina; fissile, 34.

Laurentian system, 66-69; origin of the
term, 66; rocks of the system, 68;
fossils of the system, 69; physical
aspects of, 72.

Lava, an Italian term, now universally
applied to all molten rock-matter dis-

charged from volcanoes, 25, 36, 54.
Lead, veins of, in mountain limestone, 101.
Leguminosites, fruits of the tertiary
epoch, 140.

Lepidodendron, a carboniferous fossil,
98; permian, 106.

Lias, or Liassic strata, 117.

Lignite (Lat. lignum, wood), a variety of
coal, 36; occuring in oolite, 125; in
tertiary beds, 142.

Limestone, as a rock compound, 36;
uses of, 101.

Limuloides, carboniferous crustacean,
figured, 95.

Lingula, figured, 71, 76; lingula flags, 70.
Lithology, as distinguished from palæ-
ontology, 67.

Littoral (Lat. littus, the shore), applied
to all deposits and operations taking
place near or along the shore, in con-
tradistinction to pelagic (pelagus, the
deep sea) or deep-sea deposits.
Lituites, silurian chambered shell, 76.
Llanberis slates, lower Cambrian, 70.
Llandeilo rocks, the lowest series of sil-
urian strata, 69.

Lodes and veins of mineral matter, 33.
Lossiemouth,'reptiliferous sandstones of,

110.

Ludlow rocks, the upper series of silurian
strata, 75.

MAGNESIAN limestone, a member of the
permian system, 102. Any limestone
containing a notable percentage of car-
bonate of magnesia is termed " mag-
nesian."
Mammoth, or post-tertiary elephant, fig-
ured, 160.

Manua Loa, eruption of, in 1855, 164.
Marble, as distinguished from limestone,
36; marbles of the metamorphic rocks,
61; of the carboniferous, 95; of the
oolite, 125.

Marine deposits, post-tertiary, 153.
Marl, nature and composition of, 36.
Mastodon, a post-tertiary pachyderm,
figured, 147.

Mechanical suspension as distinguished
from chemical solution, 19.
Megalichthys (Gr. megale, great, and
ichthys, fish), a fish of the coal epoch,

96.

Megalonyx, a gigantic edentate mammal
from the upper tertiaries of South
America, 147.

Megatherium (Gr. mega, great, and the-
rion, wild beast), a tertiary mammal,
141.

Mesozoic (Gr. mesos, the middle, and zoe,
life), as applied to fossiliferous strata,
42, 166.

Metals, their mode of occurrence, 36.
Metamorphic system, origin and descrip-
tion of, 57-65.

Mica-schist, as a rock, 36, 58; as a rock-
group, 57-61.

Microlestes, a mammal of the triassic
period, 110.

Millstone grit, a subdivision of the car-
boniferous rocks, 96.

Miocene, or middle tertiary group, 135.
Monoclinal strata, 31.

Moraine, a Swiss term for the mounds of
detritus (sand, gravel, and boulders)
brought down by glaciers, 146.
Mountain limestone, or carboniferous
limestone, 93-95.

Murchisonia (after Murchison), a whorled
palæozoic univalve, 76.

Muschelkalk (Ger. muschel, shell, and

kalk, lime), a member of the trias, 109.
Mussel-beds, or "Mussel-binds," thin
shelly layers occurring in the coal-
measures, 98.

NEOCOMIAN, a synonyme of the green-
sand, 127.

Neozoic (Gr. neos, new, and zoe, life), as
applied to fossiliferous strata, 42.
Nerinæa, a characteristic shell of the
oolite, 121.

Neuropteris, a fern of the coal-measures,

98.

New Red Sandstone, subdivisions of, 101.
New Zealand, recent upheaval of coast,
26, 162.

Nipadites, tertiary fruit, 140.

Odontopteris, carboniferous fern, 98.
Old Red Sandstone system, or Devonian,
79-88; lithology of, 82; fossils of, 83-
85; scenery of, 86; where found, 87;
uses of, 88.

Oldhamia, figured, 71, 76.

Olenus, Cambrian trilobite, figured, 71.
Oolitic system, description of, 115-125;
subdivisions of, 116; oolite group, 118.
Orbitolite limestone of America, 137.
Organic accumulations, of recent growth,
153.

Organic agencies, their mode of opera-
tion and results, 20, 152.
Ornithichnites, fossil footprints of birds,
140.

Ornitholites (Gr. ornis, bird, and lithos,
stone), undetermined fossil remains of
birds, 140.

Orthoceras, Orthoceratite (Gr. orthos,
straight, and keras, a horn), a genus of
straight horn-shaped chambered shells,

76.

Ossiferous caves, gravels, and breccias,
160.

Osteolepis, a fish of the old red sand-
stone epoch, 85.

Outcrop, of extreme edge of inclined
strata, 31.

Outlier, or detached portion of a forma-
tion, 31.

Overlying, as applied to overflows of
igneous rocks, 32.

PALEONISCUS, paleozoic fish, 106.
Palæontology, as distinguished from lith-
ology, 67.

Palæosaurus (Gr. palaios, ancient, and
saurus, a lizard), in permian strata,

106.

Palæotherium, tertiary mammal, 140.
Palæozoic (Gr. palaios, ancient, and zoe,
life), as applied to certain fossiliferous
strata, 42.

Palmacites, fossil palms of the oolite, 120.
Paradoxides, Cambrian trilobite, figured,
71.

Peat, peat-moss, formation of, 20, 36, 158.
Pebbles, Scotch, from trap-rocks, 88.
Pecopteris, a fern-like fossil in coal-mea-
sures, 98; in permian strata, 106; in
oolite, 120.

Pelagic (Gr. pelagos, the sea), applied to
deep-sea deposits and operations, as
distinguished from shore or littoral

ones.

Pelagornis (Gr. pelagos, the sea; ornis,
bird), a gigantic tertiary bird, appar-
ently allied to the albatross, 140.

lower tertiary, 137.

OBSIDIAN (Gr. opsianus), a compact vit-
reous lava or volcanic glass; so called
from being polished by the ancients,
and used for looking-glasses, 54, 56.
Oceanic currents, effects of, 153.
Ochre, hydrated oxide of iron, as derived
from coal-measures, 91.

encrinite, 95.

Periclinal strata, 31.

Permian system, described, 102-108;
rocks of, 104; fossils of, 106; economic
products, 108.

Petalodus, palatal tooth, 95.
Petraphiloides, tertiary fruits, 140.
Petrify, Petrification (Lat. petra, a stone,
and fio, I become). All vegetable or

Phascolotherium, oolitic mammal, 122.
Pisolite, or peastone, in oolite, 118.
Pitchstone, and pitchstone porphyry,
varieties of igneous rocks, so termed
from their pitch-like lustre, 107.
Placoid, Placoidians, &c., a division of
fishes, 84.
Plagiaulax, an abbreviation for Plagi-
aulacodon (Gr. plagios, oblique; aulax,
groove; and odous, tooth), an herbivor-
ous marsupial of the oolite, so called
from the diagonal groovings of the pre-
molar teeth, 122.

Platemys, marine tertiary turtle, 140.
Platysomus (Gr. platys, broad, and omos,
the shoulder), a ganoid fish of the per-
mian epoch, 106.

Pleistocene, a synonyme of the "Drift."
134; nature and composition of, 143-
167.

Plesiosaurus, a sauroid of the oolitic sys-
tem, 122.

Pliocene, the upper group of the tertiary
system, 136.

Poikilitic, a term formerly applied to the
new red sandstone, 102.

Polype (Gr. polys, many, and pous, a
foot), the zoological term applied to
zoophytes having many tentacula or
feet-like organs of prehension; hence
also the term polypidom, 22.
Porphyry (Gr. porphyreos, purple), origi-
nally applied to a reddish igneous rock
used in Egyptian architecture, but
now applied to all igneous rocks hav-
ing detached crystals (mostly of fel-
spar) disseminated through the mass;
hence the term porphyritic. We have
thus porphyritic granites, greenstone
porphyries, felspar porphyries, trachy-
tic porphyries, and so forth, 50.
Portland stone, a stratum of the upper
oolite, 125.

Post-tertiary, or recent accumulations,

148-164.

Potstone, a soft magnesian rock, the
lapis ollaris of the ancients, 61.
Primary, Primitive, in geological classi-
fication, 39.

Productus, a bivalve characteristic of
the carboniferous limestone, 95; in
magnesian limestone, 106.
Protogine (Gr. protos, first, and ginomai,
I am formed), a granitic rock, 36, 46.
Protosaurus (Gr. protos, first, and saurus,
a lizard), in permian strata, 106.
Psammodus, palatal tooth, 95.
Psilophyton, old red sandstone plant, 83.
Pterichthys, fish of the old red sandstone,
84.

Pterodactyle, a flying sauroid of the
oolite, 122.

Pterophyllum (Gr. pteron, a wing, and
phyllum, a leaf), fern-like fossils of the
oolite, 120.

Pterygotus, a peculiar crustacean of the
old red sandstone, 76, 83.
Puddingstone or conglomerate, 36, 44.
Pumice (Ital. pomice, allied to spuma,
froth or scum), a light, porous, froth-
like lava, 25, 54, 56.
Puozzolana, uses of, 56.

Pyrites (Gr. pyr, fire), sulphurets of
iron or of copper, 36; in slate, 62; in
coal, 101; in lias, 117.

QUAQUAVERSAL (Lat., on every side).
This term is applied to strata which
dip in every direction from a common
point or centre of elevation.
Quartz, nature and composition of, 36;
quartz-rock, or quartzite, 59.
Quaternary, or post-tertiary system, 148-
164.

RAGSTONE, applied to coarse concretion-
ary or breccio-concretionary rocks, as
coral rag, Kentish rag, &c.

Retepora (Lat. rete, a net, and porus, a
pore), a flustracea-like zoophyte found
in various formations, 95.
Ripple-mark on sandstones, 87.
Rivers, their effects as geological agents,
17, 147.

Rock, geological application of the term,
28; description of various rocks, 36;
classification of, into systems and
groups, 37-42.

Rock-salt, deposits of, in England, 110.
Roestone, or oolite, as distinguished
from pisolite, 118.
Rhynchosaurus, triassic reptile, 110.

SACCHAROID (saccharum, sugar; eidos,
like), like loaf-sugar in texture, 35.
Saddle-back, a familiar term for anti-
clinal strata, 31.
Sal-ammoniac, uses of, 56.
Saliferous (Lat. sal, salt, and fero, I
yield), a term applied to salt-yielding
strata, 102.

Salt, Cheshire deposits of, 114; lake de-
posits of, 157.

Salts, combinations of acids and bases,
as rock-salt, potash, soda, &c., 36.
Sand, sandstone, descriptions of, 36.
Sand-dunes (Brit. dune, a hillock), sand-
drift, occurrence of, 16, 20.
Sauroids (Gr. saurus, a lizard), of the lias,
oolite, and wealden, 122.

Scaphite, a chambered boat-shaped shell
of the chalk, 129.

Scar, a bluff precipice of rock; hence
"scar limestone" applied to the moun-
tain limestone, as it occurs in the hills
of Yorkshire and Westmoreland.
Schist, as distinguished from slate, 59.
Schorl, or black tourmaline, an acciden-
tal mineral, in granitic rocks, 47.
Scolites (Gr. skolios, tortuous), tortuous

tube-like worm-burrows that occur in
many sandstones, 76.
Scoriæ (Ital. scoria, dross), volcanic cin-
ders or cindery-like accumulations,
43, 54.

Seam, restriction of the term, 34.
Secondary, in geological classification, 39.
Section (Lat. sectus, cut). The line,
actual or ideal, which cuts through
any portion of the earth's crust so as
to show the internal structure of that
portion (just as one would slice a loaf,
or saw up a tree), is termed a Section,
32.
Sediment (Lat. sedere, to settle down),
various kinds, as river, lake, and
oceanic, 18.

Sedimentary rocks, description of, 29.
Selenite (Gr. selene, the moon, and ites,
for lithos), as distinguished from ordi-
nary gypsum, 36.

Septaria (Lat. septum, a division or
fence), applied to nodules of ironstone,
&c., occurring in the shales of the coal-
measures, lias, and other strata, be-
cause, when broken up, the interior is
often divided into net-like compart-
ments by minute veins of carbonate of
lime, 117.

Series, applied to a number of allied

strata arranged in sequence, or order
of superposition, 41.

Serpentine, a mottled magnesian rock,
so called from its serpent-like colours,
36, 46.

Shale (Ger. schalen, to peel or shell off),
applied to all argillaceous strata that
split up or peel off in thin laminæ, 36.
Shell-beds, growth and accumulation of,
21, 159.

Shingle, loose imperfectly rounded stones
and pebbles, as distinct from gravel
and sand, 36.

Sigillaria, a stem characteristic of the
coal epoch.

Silicious springs (Lat. silex, flint), or
those holding silicious matter in solu-
tion, 17.

Silt, fine mud, clay, or sand deposited
as a sediment from water, 7, 36.
Silurian system described, 74-79; mean-
ing of the term, 75; rocks of, 75; fos-
sils of, 76; extent of, 77; uses of, 79.
Sinter (Ger. sintern, to drop or incrust
by dropping), hence, calc-sinter and
silicious-sinter, 17, 23.

Skaptar Jokul, eruption of, in 1783, 164.
Slate, as distinguished from shale, 36.
Soil, growth and nature of, 161.

Solfatara (Ital. solfo, sulphur), a vol-
canic fissure or orifice from which sul-
phureous vapours, hot mud, and steam
are emitted.
Spalacotherium, mammal of the oolite,

122.

Spar (Ger. spath), a mineralogical term
applied to those crystals or minerals
which break up into rhombs, cubes,
plates, prisms, &c., with smooth cleav-

193

Stratified rocks, synonymous with aque-
ous and sedimentary, 30.

Stratum (singular), Strata (plural), mean-
ing of, 3; horizontal, inclined, bent,
and vertical, 31; structure of various
strata, 34.

Strike, the linear direction of any stra-
tum as it appears at the surface, 31.
Structure of rocks, 34.

Stylonurus, a crustacean of the silurian
and old red sandstone, 76, 83.

Sub (Lat. under), often applied in geo-
logy to express a less degree of any
quality, as sub-columnar, not distinct-
ly columnar; sub-crystalline, indis-
tinctly crystalline: applied also to
position, as sub-cretaceous, under the
chalk.

Sub-fossil, partly fossil, 148.

Submarine or Submerged forests, 155.
Sulphur, as a volcanic product, 54, 56.
Superposition of rock-formations, 38,

41.

Syenite, a granitic rock, mineral compo-
sition of, 36, 46, 59.

Syncline, synclinal axis or trough, 31.
System, limitation of the term, 40, 42.

TALC as a rock, 36; talc-schist, 38.
Talus, the sloping accumulation of de-
bris which takes place at the base of
a cliff or precipice exposed to the
weathering effects of frost, rains, and
other atmospheric agents.
Telerpeton, a reptile of the triassic (?)
epoch, 85.

Tertiary, in geological classification, 39.
Tertiary system, described, 135-143.
Tetrapodichnites (Gr. tetra, four; pous,
podos, the foot; ichnon, a footprint;
and ites), 110.

Texture of rocks, 34.

Thecodontosaurus (Gr. theke, a sheath;
odous, tooth; and saurus, lizard), a
permian saurian; so called from the
sheath or cone-in-cone-like structure
of its teeth, 110.
Thermal (Gr. therme, heat), applied to
hot springs and other waters whose
temperature exceeds 60° Fahr., 23, 156.