Earth Sculpture; Or, The Origin of Land-forms |
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Page xi
... Ridge , Green River Plains ( Powell ) . Isoclinal Folds 27 . 28. Isoclinal Folds 29 . Isoclinal Folds 30. Overfold passing into Reversed Fault , or Overthrust PAGE ˇ 7 ˇ 9 IO 10 II 41 51 54 58 62 69 74 74 75 77 78 79 80 84 84 86 87 88 ...
... Ridge , Green River Plains ( Powell ) . Isoclinal Folds 27 . 28. Isoclinal Folds 29 . Isoclinal Folds 30. Overfold passing into Reversed Fault , or Overthrust PAGE ˇ 7 ˇ 9 IO 10 II 41 51 54 58 62 69 74 74 75 77 78 79 80 84 84 86 87 88 ...
Page xii
... Ridges of Pennsylvania ( H. D. Rogers ) 118 55. Unsymmetrical Folds , giving rise to Escarpments and Ridges 56. Structure of the Ardennes ( after Cornet and Briart ) . 57. Diagrammatic Section across a Plateau of Erosion 120 126 • 129 ...
... Ridges of Pennsylvania ( H. D. Rogers ) 118 55. Unsymmetrical Folds , giving rise to Escarpments and Ridges 56. Structure of the Ardennes ( after Cornet and Briart ) . 57. Diagrammatic Section across a Plateau of Erosion 120 126 • 129 ...
Page 14
James Geikie. The ure and underground structure can be traced . mountain ridges do not correspond to great swellings of the crust ; the valleys neither lie in trough - shaped strata , nor do they coincide with gaping fractures . Again ...
James Geikie. The ure and underground structure can be traced . mountain ridges do not correspond to great swellings of the crust ; the valleys neither lie in trough - shaped strata , nor do they coincide with gaping fractures . Again ...
Page 46
... ridges which they sometimes traverse ; or , to put it in another way , new mountains may come into existence without deflecting the rivers across whose valleys they may seem at one time to have extended - for the rivers have simply ...
... ridges which they sometimes traverse ; or , to put it in another way , new mountains may come into existence without deflecting the rivers across whose valleys they may seem at one time to have extended - for the rivers have simply ...
Page 65
... ridges gradu- ally crumble down , until at last all abrupt and pro- minent irregularities of surface disappear , and the once elevated plain returns to its former state , that of a gently undulating or approximately flat stretch of low ...
... ridges gradu- ally crumble down , until at last all abrupt and pro- minent irregularities of surface disappear , and the once elevated plain returns to its former state , that of a gently undulating or approximately flat stretch of low ...
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Common terms and phrases
accumulation Alps anticlines basalt base-level basins become beds Carboniferous character cliffs coast-lines cones configuration Cretaceous crust crustal movements crystalline débris denudation deposits depressions depth detritus direction dislocations drainage elevation epigene action epigene agents eroded eruption escarpments eventually feet fiords flexures flow fluvio-glacial deposits folds fracture gently geological structure glacial action glaciers gradually granite ground-moraines Highlands hills hollows horizontal strata ice-sheet igneous rocks inclined indented infrequently irregular islands joints Jura Mountains laccoliths lakes land land-forms land-surface lava less limestone low grounds masses materials Mesozoic modified moraines mountain-chain mountain-valleys mountains normal faults Old Red Sandstone outcrops owe their origin Permian plain of erosion plateau regions relatively result ridges rock-basins rock-masses sand schistose schists Section sediment shales Silurian slopes Southern Uplands strata streams and rivers superficial surface surface-features synclinal tectonic tend thickness tion tracts traversed underground undulating usually valleys vertical volcanic
Popular passages
Page 366 - THERE rolls the deep where grew the tree. O earth, what changes hast thou seen ! There where the long street roars, hath been The stillness of the central sea. The hills are shadows, and they flow From form to form, and nothing stands; They melt like mist, the solid lands, Like clouds they shape themselves and go.
Page 331 - ... position, undisturbed by crustal oscillation, for a prolonged period of time, they will eventually be cut back by the sea. In this way a shelf or terrace will be formed, narrow in some places, broader in others, according to the resistance offered by the varying character of the rocks. But no long inlets or fiords can result from such action. At most the harder and less readily demolished rocks will form headlands, while shallow bays will be scooped out of the more yielding masses. In short,...
Page 67 - Those who have long and carefully studied the Grand Canon of the Colorado do not hesitate for a moment to pronounce it by far the most sublime of all earthly spectacles. If its sublimity consisted only in its dimensions, it could be sufficiently set forth, in a single sentence. It is more than 200 miles long, from 5 to 12 miles wide, and from 5,000 to 6,000 feet deep.
Page 146 - ... Highlands, when viewed from a commanding position, looks like a tumbled ocean in which the waves appear to be moving in all directions. One is also impressed with the fact that the undulations of the surface, however interrupted they may be, are broad — the mountains, however they may vary in detail according to the character of the rocks, are massive, and generally roundshouldered and often somewhat flat-topped, while there is no great disparity of height amongst the dominant points of any...
Page 308 - The following quotation comes after a description of the rock walls of the fiords: Numerous tributary waters, some of which are hardly less important than the head-stream, do indeed pour into the fiord, but they have not yet eroded for themselves deep trenches. After winding through the plateauland in broad and shallow valleys their relatively gentle course is suddenly interrupted^ and they at once cascade down the precipitous rock-walls to the sea. The side-valleys that open upon a fiord are thus...
Page 331 - To sum up, then, we may say that the chief agents concerned in the development of coast-lines are crustal movements, sedimentation, and marine erosion. All the main trends are the result of elevation and depression. Considerable geographical changes, however, have been brought about by the silting up of those shallow and sheltered seas which, in certain regions, overflow wide areas of the continental plateau. Throughout all the ages, indeed, epigene agents have striven to reduce the superficial inequalities...
Page 177 - The lava of the Henry Mountains behaved differently. Instead of rising through all the beds of the earth's crust, it stopped at a lower horizon, insinuated itself between two strata, and opened for itself a chamber by lifting all the superior beds. In this chamber it congealed, forming a massive body of trap.
Page 310 - ... Why should the erosion of the main or fiord-valleys be so immeasurably in advance of that of the lateral valleys ? Obviously there must have been a time when the process of valleyformation proceeded more rapidly along the lines of the present fiords and their head-valleys than in the side-valleys which open upon these from the fjelds. At that time the work of rain and running water could not have been carried on equally over the whole land, otherwise we should find now a completely developed...
Page 178 - They lie in clusters, and each cluster is marked by a mountain. In Mount Ellen there are perhaps thirty laccolites. In Mount Holmes there are two; and in Mount Ellsworth one. Mount Pennell and Mount Hillers each have one large and several small ones.
Page 378 - Second, we have the proofs of former glaciation afforded by striated rocks and roches moutonuees and by the crushed, broken, tumbled, and confused rock surfaces that occur so frequently underneath the bottom or ground moraines. Third, we have the presence of certain remarkable ridges of gravel and sand which appear to have been formed in tunnels under the ice, and of enormous sheets of similar materials which have been spread out by the waters escaping from the terminal front of the inland ice of...