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Scoriae (Gr. tkoria, dross): loose fragments of slaggy, cindery lava.

Screes (Icel. skritha, fallen rocks on a hillside): a Westmoreland term for the sheets of loose angular stones which gather upon hillsides and at the base of cliffs, etc.

Shearing: the yielding of a rock to compression, strain, and tension during crustal movements, whereby the solid mass is compelled to flow, so that a kind of fluxion-structure is developed in it; frequently under such conditions dislocation takes place—the rock gives way and one mass is pushed over another.

Sheet: molten matter intruded between bedded rocks.

Stalactites (Gr, stalaktos, dropping): the icicle-like pendants hanging from the roofs of limestone caves, formed by the drip of water holding carbonate of lime in solution.

Stalagmites (Gr. stalagmoi, a dropping): the calcareous deposit formed upon the floor of a cavern by the drip of water from the roof.

Stoss-seite: see Lee-seite.

Strix, glacial: scratches, furrows, etc., engraved upon rock-surfaces by glacial action.

Strike: the general direction or run of the outcrops of strata.

Swallow-holes: see Dolina. ,

Syenite (from Syene, Egypt): a holocrystalline igneous rock of deep-seated origin.

Syncline (Gr. syn, together; klino, I lean) : a basin or trough-shaped arrangement of strata; the strata dip from opposite directions inwards to one common axis. When the axis is vertical the syncline is symmetrical; when inclined, unsymmetrical.

Systems : the larger divisions of strata included under the Palaeozoic, Mesozoic, Cainozoic, and Quaternary groups.

Terrigenous: applied to marine accumulations the materials of which have been derived from land; opposed to abysmal, applied to marine deposits the constituents of which have not been so derived.

Thrust-plane: a Reversed fault (a. v.), the hade or inclination of which approaches horizontally; a common structure in regions of highly flexed rocks.

Till: another name (Scottish) for Boulder-clay (a. v.).

Tors: the peculiar and often fantastic prominences met with in regions of granite which have been long exposed to weathering, as on Dartmoor. The kopjfs of Mashonaland are an example of the same phenomenon.

Trachyte (Gr. trachys, rough): a hemicrystalline volcanic rock.

Travertine: another name for Calc-sinter (,/. v.).

Triassic (Gr. trins, three): one of the Mesozoic systems.

Tufa, or calcareous tufa: same as Calc-sinter, Travertine (q. v.).

Tuff: a volcanic fragmental rock; usually applied to the finer-grained ejectaof volcanic eruptions; may consist almost entirely of lapilli (q. v.) or of the finest sand and dust, or of a mixture of coarse and fine ingredients.

Unconformable : not conforming in position, or not having the same inclination or dip with underlying rocks; applied to strata which rest upon an eroded surface of older rocks; unconformity or unconformability, the condition of not being conformable.

Underclay: the bed upon which a coal-seam rests.

Uniclinal (L. units, one ; Gr. klino, to lean): applied to a series of strata dipping in one and the same direction.

Upthrow, upcast: that side of a fault on which the strata lie at a higher level than their continuations on the other side of the fault. Normal faults are usually described as downthrows; reversed faults as upthrows.

Wady(Ar.): a ravine or watercourse, dry except in the rainy season. Some wadies are perennially dry.

Weathering: applied to the decomposition, disintegration, and breaking up of the superficial parts of rocks under the general action of changes of temperature, and of wind, rain, frost, etc.

Zeolites (Gr. zeo, I boil; lithos, stone): a group of minerals, so called because they bubble up in the blowpipe flame; often met with filling up vesicular cavities, etc., in igneous rocks.

INDEX

Aar Glacier, 215

Abrasion by ice, 21(>, 241, 248

Abyssinia, plateaux of, 186, 339

Accumulation-mountains, 340

Achumore, 97

/Kolian action, 24, 250

— basins. 257. 260. 284
African coasts, 328

— lakes, 162, 279
Afton Water. 138
Air volcanoes. 185
Aix-la-Chapelle. 127
Akabah, gulf, 151J
Aletsch Glacier, 306
Alluvial basins, 283

— terraces, 7, 49, 50

Alpine glaciers, work done by, 213,
217

— lands, glacial phenomena of, 227,

246, 247
Alps, the, 93, 109, 1lq, 208, 214, 216,

217, 231, 284, 291, 293, 296, 312,

351
Amazon, delta, 52

— river, 7
Andes, cirques, 292
Andesite, 174, 201

Animals, geological action of, 29
Annan Water. 133
Anticlinal double-fold, 96

— hills and mountains, 88,91,104, 111

— valleys, 10, 85, 86, 112, 116, 117
Anticlines, symmetrical, 85, 86,^88,

90, 105, 112, 115, 117, 119

— unsymmetrica], 10, 93, 94, 99, 107,

116, 120
Antilcbanon, 162
Antrim, basalts, 186, 191
Appalachian Mountains, 93, 118

Aqueous rocks, 3, 4, 22
Arabah Mountains, 250

— Wady, 159

Aralo-Caspian depression, 52, 279,

337
Ardennes Mountains, 127
Argillaceous rocks, 21
Arizona, 53

Arkansas, aeolian basins of, 284
Auvergne, caves, 275

— lakes, 281
Axial uplift. 129

Bahia, 257, 284

lialtic (ilacier, 247, 306

pay sage morainiaur, 247
Haltzcr, Prof., 221
Iiamlaisan, 2S2

Barrier lakes, 281, 293, 29.S, 305
Basalt, 20, 21, 174

— caves, 276

— plams and plateaux, 180

— sea-cliffs. 324

— weathering, 26, 201

Base-level of erosion, 59, 63, 66, 87,

140, 143, 149, 226. 343, 360
Basins, origin and classif1cation, 278,

279. 3?9
Bathgate H1lls, 345
Bavarian Alps, 112
Beach gravels, 325
Belgium, carboniferous districts, 127
Ben Alligin. 147

— Dearg, 147

— Eighe. 147

— Lomond, 142

— Muich Dhui, 142

— Nevis, 142

— Uidhe, 97

Berendt. Prof. G., 260

Berlin, 233

Bertrand, Prof. M., 95

Bex, 297

Bingen, 165

Birnam, 169

Black earth, 263

— Forest, 163
Blind valleys, 271
Bol1m, Dr., 229

Bottom moraine, see Ground-moraines
Boulder-clay, composition of, 233

— configuration of, 233

— marine erosion of, 319
Boulogne, 127
Bowdoin Glacier, 224
Bracciano, lake, 281
Brandenburg, 238
Brazil, coasts, 329, 330

— schistose rocks, 6

— weathered rocks, 205
Briatt, M., 127
Brick-clay, 21

British mountains, 93
Buttes, 59, 344, 376

Cairngorm Mountains, 290
Caithness pyramidal hills, 71
Calcareous rocks, 208
Caldeiraos, 257
Caledonian Canal, 144
Californian lava-caves, 275
Cambusnethan, 167
Canada, schistose rocks, 6

— lakes, 301

Canary Islands, lava-caves, 275

Canisp, 71

Cations of Colorado, 53, 66

Cape Blanco, 257

Cape Bojador, 257

"Capture" by streams, 108, 122, 131,

138, 144, 148
Carinthia, Karst-regions, 271
Cam Chois, 146
Carpathian Mountains, 115
Cascades, see Waterfalls
Caucasus, 119
Caverns, 31, 209, 269, 272-277, 282,

325
Cevennes, 208
Chalk, 22

— escarpments, 83, 84, 345
Chamberlin, Prof., 220, 223

Changes of sea-level, 12, 13
Chemical action of rain, 25

— of underground water, 30, 267
Chilian Andes, 292

Chiltern Hills, 345
China, dust deposits, 261
Choffat, P., 116
Cinder cones, 181, 182
Circumdenudation mountains, 133,

'45. 147. 193, 204, 346
Cirque basins, 287

— lakes, 286

— valleys, 70, 290
Classification of land-forms, 335
Clermont, 275

Cliffs, river-, 61, 6S, 72, 76, 353

— sea-, 71, 319

— undercut by wind-action, 24
Climate, influence of, on denudation,

64, 72, 370
Coal, 4, 23
Coastal plains, 326
Coast-lines, general trend, 317, 328,

361
Coasts, indented or irregular, 327

— smooth or regular, 325
Colorado Plateau, 344

— faults of, 156

— river, 53, 57, 67, 156
Como, lake, 293, 298
Concretions, 256

Cone-in-cone structure of volcanoes,

183
Conglomerate, 3, 22
Connel Water, 138
Constance, lake, 293, 298
Constriction-basins, 299, 302
Constructional valleys, 347
Continental plateaux, 339
Coral reefs, 334
Cordilleras, 93, 119
Cornet, M., 127
Cornwall, sea-caves, 276
Corrie, see Cirque.
Cotswold Hills, 83, 345
Coulmore, 71
Crag-and-tail, 242
Crater lakes, 281
Cree, river, 133
Crevasses in glaciers, 216, 218
Crieff, 192
Crustal deformation, 13, 47, 48, 179,

209, 280, 330

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