Bulletin of the Geological Society of America, Volumen7Geological Society of America, 1896 Vols. for 1938-61 include as pt. 2 of the December issue the Society's Abstracts, later published separately. |
Contenido
| 363 | |
| 370 | |
| 373 | |
| 376 | |
| 377 | |
| 388 | |
| 399 | |
| 404 | |
| 75 | |
| 81 | |
| 87 | |
| 95 | |
| 102 | |
| 108 | |
| 115 | |
| 135 | |
| 171 | |
| 219 | |
| 255 | |
| 315 | |
| 327 | |
| 349 | |
| 411 | |
| 414 | |
| 417 | |
| 423 | |
| 424 | |
| 431 | |
| 438 | |
| 441 | |
| 453 | |
| 455 | |
| 506 | |
| 532 | |
| 549 | |
Otras ediciones - Ver todas
Términos y frases comunes
altitude ambulacral plates ambulacrum apatite appears Archæocidaris augite bands beds boulder-clay boulders Bow river catalogue number coarse columns of plates coreyi creek Cretaceous crystals denudation deposits described dorsal drift drumlins Echini elevation ellipsoidal Eocene erosion feet feldspar feldspathic figure formation Four columns genus Geol glacial gneiss gneissic grains granular heptagonal heptagonal plate hexagonal hornblende ice-sheet inclosed initial plate interambulacral areas interambulacral plates interambulacrum irregular lake Laurentian Lepidechinus limestone lower masses Matanzas Melonites giganteus Melonites multiporus microcline miles Miocene moraines mountains Museum of Comparative number of columns observed occur Oligoporus Paleozoic paper peneplain pentagon peristome plagioclase plains Porcupine hills portion Professor pyroxene pyroxenite quartz quartzite region Rhoechinus ridges river rock row of plates sand sandstone seen shown side sixth column species specimen spines stage strata streams structure surface syenite-gneiss terminal pentagon terraces Tertiary thickness tion upper valley ventral border
Pasajes populares
Página 2 - The report was accepted as a report of progress, and the committee was continued, with the addition of the President to its membership.
Página 189 - Melonites, it is with great satisfaction that I am able to state that the four genera may be most intimately and serially connected by a study of the growth of the ambulacrum. The four genera represent a distinct phylum, which is progressively advancing in the line of increase of columns of ambulacral plates. Etheridge (11) has pointed out already from a consideration of the adult that Oligoporus seems to be intermediate between Rhoechinus, (Paliechimis*) and Melonites, having twice the number of...
Página 260 - ... reduced to the condition of a soft paste, exhibiting all the mineralogical elements of the rocks, as they may have been before they were decomposed, but now completely disintegrated and resting side by side, as if they had been accumulated artificially...
Página 377 - The sea has really had less to do than the meteoric agents. A ' plain of marine denudation ' is that sea-level to which a mass of land had been reduced mainly by the subaerial forces, the line below which further degradation became impossible, because the land was thereafter protected by being covered by the sea. Undoubtedly the last touches in the long process of sculpturing...
Página 21 - Whenever the warm climate terminating the Glacial period extended unchecked through many years, the depth of the ablation or superficial melting of the outer part of the ice-sheet was probably not less than 15 to 25 feet each summer, as has been observed on the Muir glacier in Alaska! and on the Mer de Glace in Switzerland.
Página 349 - A glance at this table is sufficient to show that the disintegration is accompanied by decomposition and a leaching action which has resulted in the removal of a portion of the more soluble constituents. The fact that the fresh rock yields the larger percentages of its constituents to the solvent action of acid and alkaline solutions is readily explained on this ground, though I doubt if the full significance of the fact, so far as it relates to silicious crystallines, is as yet appreciated.
Página 306 - This principle is employed in the process of gold wiishing known as "booming." ing November, and this may be true not only of one but of several of the months. Traveling in the interior of the country at certain seasons of the year, one is impressed by the dry beds of what are, at other times, large rivers. This is especially striking in the northeastern part of Brazil, through the interior of Bahia, Pernambuco, Parahyba. Rio Grande do Norte, Ceara, and Piauhy. Streams that are at one season large...
Página 106 - The fruit bodies vary in size from a few inches to a foot or more in diameter and may be shaped like pancakes or thick brackets. They are soft, but rather tough and, when young and fresh, have quite a pleasant " mushroomy " smell, but when old and decomposing may give rise to foul odours.
Página 272 - ... very steeply inclined, the beds are not so vertical as in the southern prolongation of the range. The consequence of this difference is the formation of more massive and less disconnected summits on the north side ; while on the south side, where the strata are nearly or quite vertical, the harder sets of beds alone have remained standing, the softer intervening beds having been gradually disintegrated. By this process have been formed those strange peaks which appear from a distance like a row...
Página 27 - ... drift. Only with a rate of ablation much faster and with glacial currents much stronger than those of the Arctic regions or of the continental icesheets during their time of accumulation under the severe climate of their high plateau elevation, in short, only during the Champlain epoch, when the land had sunk from its preglacial and glacial altitude both in America and Europe, could noteworthy peripheral moraines be amassed. They record on each continent the definite closing epoch of the Glacial...