Report on the Geology of Cornwall, Devon and West SomersetLongman, Orme, Brown, Green, and Longmans, 1839 - 648 من الصفحات |
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طبعات أخرى - عرض جميع المقتطفات
عبارات ومصطلحات مألوفة
accumulated adjoining appear arenaceous argillaceous slates Austell beach Beacon beds beneath Bristol Channel calcareous matter carbonaceous carbonaceous series carbonate Carn chalk character chert clay cliffs coast conglomerate considerable considered containing copper Cornish Cornwall and Devon Cove cross courses crystals Dartmoor deposits detrital direction district divisional planes east elevation elvan engine estuary fathoms feet felspar fissures formed Fowey fragments Geol geological granite grauwacke gravel green sand greenstone Gwennap Helston Hill hornblende igneous iron land lias lime limestone lodes lower Lyme Regis Marazion marls mass mica miles mineral veins mines noticed observed obtained occur organic remains Padstow Plymouth Polgooth porphyry portion produced quantity quartz raised readily red sandstone series Redruth sandstone schistose schorl sedimentary seen stone substances sulphuret suppose surface Tavistock tinners tion tons Trans trappean rocks traversed valley vicinity Wheal
مقاطع مشهورة
الصفحة 626 - In the name of God, Amen. Before you, the most reverend father in Christ and Lord, the lord Thomas, by the grace of God archbishop of Canterbury, primate of all England, and legate of the apostolic see...
الصفحة 523 - Britain ; for at full tide, the intervening passage being overflowed, they appear islands ; but when the sea returns, a large space is left dry, and they are seen as peninsulas. From hence, then, the traders purchase the tin of the natives, and transport it into Gaul ; and finally, travelling through Gaul on foot, in about thirty days they bring their burdens on horses to the mouth of the river Rhone.
الصفحة 407 - Pentuan and Carnon proved that a considerable change had taken place in the relative levels of sea and land, since man inhabited Cornwall. The mere fact of the occurrence of traces of human existence and industry at a certain depth in valley deposits did not of necessity imply any great antiquity. The special industries of Cornwall had caused large quantities of debris to wash down ; but the deposits with which he had to deal that evening...
الصفحة 471 - ... chiefly compounds of hornblende and felspar, afford the most fertile soils of any in the district, when their decomposition has taken place to any sufficient depth ; so much so, that when much disintegrated, they are sometimes worked as marl-pits for manure, and the land thus treated is always found to be greatly benefited. The trappean ash, particularly when mingled with calcareous matter, which is sometimes the case, affords a remarkably fine soil.* Limestone occurs in sufficient abundance...
الصفحة 33 - ... regulated by the sun, — there must have been a time when solid rock was first formed, and also a time when heated fluids rested upon it. The latter would be conditions highly favorable to the production of crystalline substances, and the state of the earth's surface would then be so totally different from that which now exists, that mineral matter, even abraded from any part of the earth's crust, which may have been solid, would be placed under very different conditions, at these different...
الصفحة 626 - ... of good and lawful men of your bailiwick, by whom the truth of the matter may be better known, you diligently...
الصفحة 33 - ... having been wholly gaseous, then fluid and gaseous, and subsequently solid, fluid, and gaseous, the surface at last became so reduced in temperature, and so little affected by the remaining internal heat, as to have its temperature chiefly regulated by the sun, there must have been a time when solid rock was first formed, and also a time when heated fluids rested upon it. The latter would be conditions highly...
الصفحة 282 - Indeed, the general laminated structure of the clay appears to indicate, that a series of voltaic poles were produced throughout the clay, the symmetrical arrangement of which had a corresponding effect on the structure of the clay. This view is still more strikingly confirmed by the occurrence, in several instances, of veins, or rather laminre of oxide of iron, the edges of which are shewn by the shaded lines AT, I, m.
الصفحة 267 - in numerous localities we find the coarser slates converted into rocks resembling mica-slate and gneiss, a fact particularly well exhibited in the neighbourhood of Meavy, on the south-east of Tavistock,' and ' near Camelford we observed a fine arenaceous and micaceous grauwacke turned into a rock resembling mica-slate near the granite.
الصفحة 480 - ... along the coast ; generally speaking, the harder the coast and the less the detritus that can be worn from it, the greater the proportion of the comminuted shells in a given portion of sand. The easier also the streams or rivers flowing towards the shelly sands can deposit the sandy detritus they may bring down in floods before they reach the shelly banks, the finer the sand. We have found the sands, considered worth removal for agricultural purposes, to vary from 40 to 70 per cent, in their...