Crustal Sentence Examples
The basins have been variously ascribed to glacial erosion, to obstruction of normal outlet valleys by barriers of glacial drift, and to crustal warping in connection with or independent of the presence of the glacial sheet.
A broad, low crustal arch extends southward at the junction of the Atlantic and Gulf coastal plains; the emerged half of the arch, constitutes the visible lowland peninsula of Florida; the submerged half extends westward under the shallow Florida.
In North America, the crustal movements at the beginning of the period are less evident than in Europe, but a marked parallelism exists; for in the east, in the Appalachian tract, we find detrital sediments prevailing, while the open sea, with great deposits of limestone, lay out towards the west in the direction of that similar open sea which lay towards the east of Europe and extended through Asia.
The main point to observe in this connexion is that large tracts of land in many parts of the world were at a critical level as regards the sea, a condition highly favourable to frequent extensive incursions of marine waters over the low-lying areas in a period of extreme crustal instability.
The oblique trend of the coast would be even more pronounced but for a comparatively modern crustal movement, causing a depression in the northeast, with a resulting encroachment of the sea upon the land, and an elevation in the south-west, with a resulting advance of the land upon the sea.Advertisement
The Pacific coast has been defined chiefly by relatively recent crustal deformations, and hence still preserves a greater relief than that of the Atlantic. The minor features of each coast will be mentioned in connexion with the land districts of which the coast-line is only the border.
Associated with these crustal movements were enormous outpourings of volcanic materials.
Results will define the age of the Scottish drainage divide and test models which predict divide migration in response to crustal deformation.
Simon Harley, Professor of Lower crustal Processes, is studying deep crustal metamorphism in the granulites of East Antarctica.
The aseismic nature of the continental mantle and the lower crustal seismicity beneath some shields are probably related to their water contents.Advertisement
They move deeper rocks over shallower ones and accommodate crustal shortening.
Arrange- Professor C. Lapworth has generalized the grand features meat of of crustal relief in a scheme of attractive simplicity.
In this province, therefore, we find a part of one of those ancient mountain regions, initiated by crustal deformation, but reduced by long continued erosion to a peneplain of modern relief, with occasional surmounting monadnocks of moderate height not completely consumed during the peneplanation of the rest of the surface.
The Upper Devonian was a period of marine retreat; the crustal disturbances of the Lower Devonian were renewed and great quartz-pebble beaches were formed on the rising shore lines, producing the West Coast Range conglomerates of Tasmania, and the similar rocks to the south-east of Mansfield in Victoria.
The fundamental conception of geography is form, including the figure of the earth and the varieties of crustal relief.Advertisement
The chief element of uncertainty as to the largest features of the relief of the earth's crust is due to the unexplored area in the Arctic region and the larger regions of the Antarctic, of which Crustal we know nothing.
Elie de Beaumont, in his speculations on the relation between the direction of mountain ranges and their geological age and character, was feeling towards a comprehensive theory of the forms of crustal relief; but his ideas were too geometrical, and his theory that the earth is a spheroid built up on a rhombic dodecahedron, the pentagonal faces of which determined the direction of mountain ranges, could not be proved.'
The dominant forms result from crustal movements, the subsidiary from secondary reactions o during the action of the primitive forms on mobile distri butions.
The distribution of fossils frequently makes it possible to map out approximately the general features of land and sea in long-past geological periods, and so to enable the history of crustal relief to be traced.'
The oblique trend of the coast would be even more pronounced but for a comparatively modern crustal movement, causing a depression in the northeast, with a resulting encroachment of the sea upon the land, and an elevation.Advertisement
The Pacific coast has been defined chiefly by relatively recent crustal deformations, and hence still preserves a greater relief than that of the Atlantic. The minor features of each coast will be mentioned in connection with the lani districts of which the coast-line is only the border.
In intimate relationship with the mountain-building orogenic crustal movements was the prevalence of volcanic activity during the earlier part of this period.