Bulletin of the Geological Society of America, Band 6Geological Society of America, 1893 Vols. 1-44 include Proceedings of the annual meeting, 1889-1933, later published separately. |
Inhalt
| 2 | |
| 8 | |
| 15 | |
| 18 | |
| 28 | |
| 34 | |
| 37 | |
| 103 | |
| 264 | |
| 283 | |
| 305 | |
| 315 | |
| 321 | |
| 333 | |
| 343 | |
| 353 | |
| 141 | |
| 167 | |
| 199 | |
| 221 | |
| 241 | |
| 263 | |
| 375 | |
| 389 | |
| 423 | |
| 443 | |
| 489 | |
Andere Ausgaben - Alle anzeigen
Häufige Begriffe und Wortgruppen
altitude anorthosites Antillean appears augite basin beds Caprina carbonate channel character Chazy coal Coast ranges conglomerate containing Cretaceous crystalline delta deposits depth dikes dolomite drift east elevation erosion evidence extended fault fauna feet feldspar figure fjords formation Fort Riley fossils Fusulina gabbro Geol geologic geologist glacial glaciers gneiss granite Highwood hills horizon hornblende ice-sheet indicate intrusive islands Klamath mountains lake land layers limestone lithologic locality lower magnesian Manhattan mass Meek metamorphism miles minerals Miocene moraine mountains movement northern observed occur orthoclase outcrops paper Piney Creek plain plateau Pleistocene Pliocene portion Pottsville pre-Cretaceous present probably Professor pyroxene quartz region river rocks Saint Lawrence sand sandstone schists serpentine Shakopee shales shonkinite shore side Sierra Nevada slope species Square butte strata streams submerged surface terraces thickness tion upper valley veins vertical writer
Beliebte Passagen
Seite 157 - NOVA SCOTIA Situation and population Nova Scotia consists of the peninsula of Nova Scotia and the island of Cape Breton, both lying between the Gulf of St Lawrence and the Atlantic Ocean. The area is 21,425 square miles. The...
Seite 85 - The entire freedom of the jaspers from any fragmental material deposited in the ordinary way near a shore would indicate their formation in deep or at least quiet waters. The very rare occurrence, however, of limestone in this series and the abundance of sandstone would seem to indicate the absence of deep-sea conditions during the deposition of the greater portion. No one has yet worked out the stratigraphic position of the jasper beds in the series, and ascertained if they are distributed through...
Seite 18 - Tertiary time ; but here and there isolated areas of hills and even mountains remain, consisting of remnants of the horizontal Cretaceous strata which elsewhere have suffered erosion. The most noteworthy eastern highland area of this kind is the Turtle mountain, lying in the north edge of North Dakota and the south edge of Manitoba, its extent on the boundary being about 40 miles, with two-thirds as great width.
Seite 19 - Glacial period there ntervened a second great epeirogenic uplift, as shown by a return of the conditions of vigorous stream erosion and a new cycle of partial baseleveling, by which wide flat valleys were cut in the eastern part of these Cretaceous plains. In Manitoba the northeastern border of the formerly baseleveled expanse was removed, the Cretaceous beds being eroded to the underlying...
Seite 437 - On the possibility of hemihedrism in the monoclinic crystal system, with especial reference to the hemihedrism of pyroxene: Ibid., vol.
Seite 153 - I have of late years made while in charge of the Atlantic Coast Division of the United States Geological Survey, and...
Seite 18 - When its marine and lacustrine deposits were first raised to l>e dry land they had a monotonously flat surface. A very long cycle of baseleveling ensued, beginning as soon as this northern part of the plains was uplifted at the end of Cretaceous time and continuing nearly or quite to the end of the Tertiary era. During this time the surface was gradually lowered by the action of rains, rills, rivulets, creeks and rivers, until it was mostly reduced to a baselevel of subaerial erosion.
Seite 19 - These mountains trend slightly west of north, and extend about 40 miles with a width of 15 miles, attaining an elevation of 11,178 feet above the sea and 5,000 to 6,000 feet above the prairies at their base. Their structure has been thoroughly studied by Wolff, who finds that they consist of late Cretaceous strata, soft sandstones, nearly horizontal in stratification, intersected by a network of eruptive dikes.
Seite 20 - Pawson have well pointed out, it was by the erosion of the eastern portion of these beds, after the great western expanse of the plains had received nearly its present form, that this steep escarpment was produced.* At the time of uplifting of the plains, near the beginning of the Quaternary era, this great baseleveled region appears to have stretched from the Rocky mountains to the Archean hills on the eastern border of the area of the later glacial lake Agassiz. The east margin of the soft Cretaceous...
Seite 84 - Becker,! who speaks of them as "shales silicified to chert-like masses, of green, brown, red or black colors, intersected by innumerable veins of silica." He says further: " Under the microscope the most highly indurated specimens are found to contain fossils." All observers seem to have noted the wavy, thin bedded structure and the network of quartz veins. These characters are widespread, being exhibited by the jasperoid rocks of the pre-Cretaceous series through their whole extent in the Coast...