| 单词 | porphyritic |
| 例句 | They are called “porphyry” because upper crustal stocks are typically porphyritic in texture, the result of a two-stage cooling process. Physical Geology 2015-01-01T00:00:00Z This is not to be confused with the igneous texture porphyritic, although the name is derived from the porphyritic texture that is nearly always present in the igneous rocks in a porphyry deposit. An Introduction to Geology 2017-01-01T00:00:00Z You can find dwarfs, hobbits, dragons and wizards in the towers created by porphyritic lava flows. 5 glorious backpacking routes not to miss in Eastern Oregon 2015-08-08T04:00:00Z The original porphyritic, fluidal, vesicular or fragmental structures of the igneous rock are clearly visible in the less advanced stages of hornfelsing, but become less evident as the alteration progresses. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 6 "Home, Daniel" to "Hortensius, Quintus" 2012-03-15T02:00:32.250Z At Port St. Julian, the country becomes hilly, and continues so as far to the northward as latitude 44�, the rock being porphyritic. Narrative of the surveying voyages of His Majesty's ships Adventure and Beagle, between the years 1826 and 1836 Volume I. - Proceedings of the First Expedition, 1826-1830 2012-02-24T03:00:32.793Z His marble was perhaps the porphyritic rock which it resembles when wetted by sea moisture. Nooks and Corners of the New England Coast 2012-02-22T03:00:25.113Z Those rocks examined microscopically consist of basalts which are often porphyritic. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8 "Cube" to "Daguerre, Louis" 2012-01-31T03:00:17.257Z Subsequently the porphyritic rock flowed over the surface in a pasty mass, covering the limestone. Scientific American, Vol. XLIII.?No. 1. [New Series.], July 3, 1880 A Weekly Journal Of Practical Information, Art, Science, Mechanics, Chemistry, And Manufactures 2012-01-05T03:00:30.823Z The dark-coloured porphyritic crystals of basalts are known as basaltic hornblende. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 6 "Home, Daniel" to "Hortensius, Quintus" 2012-03-15T02:00:32.250Z The geological structure of this part of the country, and a considerable portion of the coast to the north and south, consists of a fine-grained porphyritic clay slate. Narrative of the surveying voyages of His Majesty's ships Adventure and Beagle, between the years 1826 and 1836 Volume I. - Proceedings of the First Expedition, 1826-1830 2012-02-24T03:00:32.793Z The regularity of the conical shape in these peaks, which seems to point to their being of volcanic origin, renders it probable that they are either granite or porphyritic in structure. Narrative of the Circumnavigation of the Globe by the Austrian Frigate Novara, Volume II (Commodore B. Von Wullerstorf-Urbair,) Undertaken by Order of the Imperial Government in the Years 1857, 1858, & 1859, Under the Immediate Auspices of His I. and R. Highness the Archduke Ferdinand Maximilian, Commander-In-Chief of the Austrian Navy. 2012-01-03T03:00:07.630Z Many examples are banded or striated; others contain porphyritic crystals of quartz which resemble those of the felsites and porphyries. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" 2011-12-26T03:00:11.613Z An earlier generation of felspar, and occasionally also of quartz, may be represented by large and perfect crystals of these minerals giving the rock a porphyritic character. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3 "Gordon, Lord George" to "Grasses" 2011-11-13T03:00:13.177Z The gully c c to the left is very open and risky, consisting of a series of shelves formed by the falling away of the porphyritic pillars that characterise the face. Climbing in The British Isles, Vol. II Wales and Ireland 2011-09-23T02:00:23.653Z This observation is applicable to nearly the whole extent of the porphyritic country. Narrative of the surveying voyages of His Majesty's ships Adventure and Beagle, between the years 1826 and 1836 Volume I. - Proceedings of the First Expedition, 1826-1830 2012-02-24T03:00:32.793Z Compact red granite is worked at Shantallow, and the region west of Galway contains many handsome porphyritic red varieties. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 4 "G" to "Gaskell, Elizabeth" 2011-08-24T02:00:20.690Z Of its original nature there is some doubt, but its chemical composition and the occasional presence of porphyritic crystals indicate that it has affinities to the fine-grained acid intrusive rocks. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" 2011-12-26T03:00:11.613Z The rock in connection is greenstone trap, which is sometimes porphyritic. Scenes and Andventures in the Semi-Alpine Region of the Ozark Mountains of Missouri and Arkansas 2011-07-10T02:00:18.883Z When single crystals of any mineral are scattered through a rock, so as to be readily distinguished from the compact or crystalline base, the rock becomes porphyritic. Geology 2011-02-20T03:00:12.660Z Andesite is often porphyritic in character, with large crystals of felspar scattered through it. The New Gresham Encyclopedia. Vol. 1 Part 2 Amiel to Atrauli Of this range the central feature is the mountain of Kinabalu, which is composed of porphyritic granite and igneous rocks and attains to a height of 13,698 ft. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 3 "Borgia, Lucrezia" to "Bradford, John" At the base there is frequently a conglomerate or tuff of porphyritic rocks. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 2 "Bohemia" to "Borgia, Francis" Where the greenstone becomes porphyritic, the feldspar is a light green. Scenes and Andventures in the Semi-Alpine Region of the Ozark Mountains of Missouri and Arkansas 2011-07-10T02:00:18.883Z What is meant by the terms amygdaloidal and porphyritic? Geology 2011-02-20T03:00:12.660Z The lavas comprise dark pitchstone, resembling that at Kirk Yetholm, and porphyritic and amygdaloidal andesites and basalts. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" Like that, it stands upon a raised platform, built of dark porphyritic stone, the surface being five or six feet above the level of the plaza. Aztec Land Clothed at its base in a misty raiment of purple, the royal hill lifted above the valley an Olympian crest of porphyritic rock into the fathomless blue. The Strollers Whether it was granitic or porphyritic, I had no opportunity of examining, but incline to think it belonged to the latter. Rambles in the Islands of Corsica and Sardinia with Notices of their History, Antiquities, and Present Condition. The shales become dense, highly crystalline rocks of a "hornstone" type, with porphyritic developments of silicate minerals. The Economic Aspect of Geology On the other hand the most phenomenal regularity of values have been shown in certain Utah and Arizona copper mines, the result of secondary infiltration in porphyritic gangues. Principles of Mining Valuation, Organization and Administration The roadway, paved with well-cut, dark porphyritic stone, was twenty feet wide, and rested on deep foundations. Ancient America, in Notes on American Archaeology The bedded volcanic rocks which form a series of ridges trending north-west comprise porphyritic basalts, andesite, and, near Port Luchdach, brownish trachyte. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" It is made of a remarkable variety of porphyritic diorite that resembles breccia. Illustrated Catalogue of a Portion of the Collections Made During the Field Season of 1881 Third Annual Report of the Bureau of Ethnology to the Secretary of the Smithsonian Institution, 1881-82, Government Printing Office, Washington, 1884, pages 427-510 The sands and sandstones become highly crystalline quartzites, spotted with porphyritic developments of silicates. The Economic Aspect of Geology Skirting the bleak shores of Patagonia in a single narrow sierra, the Andes enter Chile, rising higher and higher till they culminate in the gigantic porphyritic peak of Aconcagua. The Andes and the Amazon Across the Continent of South America The lowest rock I saw was a compact porphyritic one. Journals of Two Expeditions of Discovery in North-West and Western Australia, Volume 2 The situation of the mines was picturesque; grand hills of porphyritic rock, and pine-forest everywhere. Anahuac : or, Mexico and the Mexicans, Ancient and Modern Other summits of the range are porphyritic,** but the hills of Wingen present a variety of rocks, within a small space. Three Expeditions into the Interior of Eastern Australia, Volume 1 Or the molten mass may come well toward the surface and crystallize more rapidly into rocks of less coarse, and often porphyritic, textures. The Economic Aspect of Geology An hour and a half below Songa, the Quorra rushes with great force through a natural gap, such it seems to be, between porphyritic rocks rising on each side of the channel. Lander's Travels The Travels of Richard Lander into the Interior of Africa The specimens, in Mr. Brown's collection from this place, consist of coarse-slaty porphyritic conglomerate, with a base of greenish-grey compact felspar, containing crystals of reddish felspar and quartz. Narrative of a Survey of the Intertropical and Western Coasts of Australia Performed between the years 1818 and 1822 — Volume 2 For some three hours we rode along among porphyritic mountains, getting higher at every turn, and enjoying the clear bright air. Anahuac : or, Mexico and the Mexicans, Ancient and Modern The rolling country east of this contained eruptive rocks—a porphyritic disbase, with zeolite, quartz, and agate of Triassic age. Through the Brazilian Wilderness He began to realize the colossal wealth which lay guarded behind the great porphyritic granite pillars. Stories from Everybody's Magazine Many of the landscapes now passed recall scenes in Algeria, especially as we get within sight of the purple, porphyritic chain of the Lozère. The Roof of France Dark grey porphyritic hornstone, approaching to compact felspar, with imbedded crystals of felspar. Narrative of a Survey of the Intertropical and Western Coasts of Australia Performed between the years 1818 and 1822 — Volume 2 The pillars were of porphyritic conglomerate, which had been disintegrated and worn away by wind and rain; while the great masses resting on them, probably of solid porphyry, had been less affected by these influences. Anahuac : or, Mexico and the Mexicans, Ancient and Modern Not at all impressed with the grandeur of the Inferno, we walked round the narrow rim of the crater-cirque, and were shown a small breach in the wall of porphyritic lava facing west. To the Gold Coast for Gold A Personal Narrative in Two Volumes.—Volume I They were of the same stuff, highly polished porphyritic granite, the pride and wonder of the avenue along which they made a burnished and flashing peristyle. Stories from Everybody's Magazine The highest mountain is Kinabalu, in the north, about 4,500 metres above the sea and composed of "porphyritic granite and igneous rocks." Through Central Borneo; an Account of Two Years' Travel in the Land of Head-Hunters Between the Years 1913 and 1917 The reach where we camped runs from north to south; and the "gate" of porphyritic trap, red, green, yellow, and white with clay, almost envelops the quartz-streaked granite. The Land of Midian — Volume 2 A cut road runs to the top of the granite tongue, which faces the westernmost or down-stream outbreaks of the huge porphyritic masses on the other side of the Wady Sadr. The Land of Midian — Volume 1 But the bulk of the moraine is composed of porphyritic granite derived from Feldspar and Cathedral Valleys. The Yosemite It was of porphyritic granite, with distinct crystals of feldspar embedded in a fine grained matrix. Stories from Everybody's Magazine These ruin-like rocks command the plain; they are composed of a coarse-grained granite, nearly porphyritic, the yellowish white feldspar crystals of which are more than an inch and a half long. Personal Narrative of Travels to the Equinoctial Regions of America, During the Year 1799-1804 — Volume 2 At a re-entering angle of the junction, a shallow pit was sunk; the sand became moist and red, and presently it was underlaid by a rubble of porphyritic trap. The Land of Midian — Volume 2 They appear to be a body of sand; but, as usual on this coast, the superficial sheet, the skin, hardly covers the syenite and porphyritic trap that form the charpente. The Land of Midian — Volume 1 We were stopped by a small circular wall of porphyritic lava, with a base of pitchstone, which concealed from us the view of the crater.* Personal Narrative of Travels to the Equinoctial Regions of America, During the Year 1799-1804 — Volume 1 The stone was hewn from a quarry of porphyritic trap near by and used for the walls in the rough. The Great Fortress : A chronicle of Louisbourg 1720-1760 These veins, two or three inches thick, are distinguished by a fine-grained quartz-granite crossing a coarse-grained granite almost porphyritic, and abounding in fine crystals of red feldspar. Personal Narrative of Travels to the Equinoctial Regions of America, During the Year 1799-1804 — Volume 2 It showed at once a complete change of formation: the sides were painted with clays of variegated colours, crystallized lime and porphyritic conglomerates, tinted mauve-purple as if by manganese. The Land of Midian — Volume 2 From the offing, also, we note how the later formations, granite and syenite, seamed with a network, and often topped by cones, of porphyritic trap, have upthrust, pierced, and isolated the older Secondaries. The Land of Midian — Volume 1 The porphyritic lavas are affected by the action of the sulphuric acid: the alumine, magnesia, soda, and metallic oxides gradually disappear; and often nothing remains but the silex, which unites in mammillary plates, like opal. Personal Narrative of Travels to the Equinoctial Regions of America, During the Year 1799-1804 — Volume 1 A larger range to the southward of it was also porphyritic, very hard, as if penetrated by quartz, and containing small crystals of flesh-coloured felspar. Journal of an Overland Expedition in Australia : from Moreton Bay to Port Essington, a distance of upwards of 3000 miles, during the years 1844-1845 The junction of Galaa Creek is remarkable for two porphyritic rock islands, situated in the bed of the river, which is here sandy, well watered, and about 300 yards wide. Narrative of the Overland Expedition of the Messrs. Jardine from Rockhampton to Cape York, Northern Queensland From the raised and metalled bank, upon which the Burj stands, we descended to the broad mouth of the Wijh valley, draining the low rolling blue-brown line of porphyritic hillocks on the east. The Land of Midian — Volume 2 Where the sandy slopes of South-Eastern Sinai-land end, appears a large white blot, apparently supporting a block, built, like a bastion, upon a tall hill of porphyritic trap. The Land of Midian — Volume 1 All are even grained, consisting of a mass of crystalline grains formed during one continuous stage of solidification, and no porphyritic crystals appear as in lavas. The Elements of Geology Some of the porphyritic rocks above mentioned are highly quartzose, others very feldspathic. The Student's Elements of Geology It is remarkable that most of the porphyritic pebbles differ from those varieties of porphyry which occur here abundantly in situ. Geological Observations on South America A tall, fissured rock, of the hardest porphyritic greenstone, high raised from the valley-sole, facing north-west, and reducible to two main blocks, is scattered over with these "inscriptions," that spread in all directions. The Land of Midian — Volume 2 The gloomy peak, which had long appeared capping the heights ahead, proved to be the culmination of a huge upthrust of porphyritic trap. The Land of Midian — Volume 1 The soil, in fact, was bestrewn with quartz and porphyritic rocks. Five Weeks in a Balloon The main body of the granite here is of a porphyritic appearance, with large crystals of feldspar; but in the veins it is fine- grained, and without these large crystals. The Student's Elements of Geology On a bare gently inclined surface of the porphyritic gneiss in Botofogo Bay, I observed the appearance represented in Figure 22. Geological Observations on South America Long before this it existed as a slate and porphyritic line of hills. More Letters of Charles Darwin — Volume 1 The apex of the gloomy porphyritic trap is a long spine of the tenderest azure-white, filmy as the finials of Milan Cathedral, and apparently melting into thin air. The Land of Midian — Volume 1 On the other side we pass over masses of porphyritic trap, in contact with the same mica schists, and these probably give to the soil the great fertility we observed. A Popular Account of Dr. Livingstone's Expedition to the Zambesi and its tributaries And of the Discovery of Lakes Shirwa and Nyassa, 1858-1864 The same lava, for example, may be glassy, or scoriaceous, or stony, or porphyritic, according to the more or less rapid rate at which it cools. The Student's Elements of Geology The porphyritic gneiss, where now exposed to the air, seems to withstand decomposition remarkably well; and I could see no signs of any tendency to the production of argillaceous masses like those here described. Geological Observations on South America To begin with the western and principal chain, we have, where the sections are best seen, an enormous mass of a porphyritic conglomerate resting on granite. More Letters of Charles Darwin — Volume 1 The next highest peaks are formed of the gypseous and porphyritic strata, thrown into vertical or highly inclined positions. Geological Observations on South America Near Paipote, also, there was much true porphyritic breccia-conglomerate: nevertheless, few of these masses were metamorphosed to the same degree with the corresponding formation in Central Chile. Geological Observations on South America Land's End, columnar granite at. —, porphyritic granite at. The Student's Elements of Geology This porphyritic formation further resembles in a singularly close manner the lowest stratified formation of the Cordillera of Chile, which, as we shall hereafter see, has a vast range, and attains a great thickness. Geological Observations on South America In the central parts of Chili the structure of the lower beds is rendered very obscure by the metamorphic action which has rendered even the coarsest conglomerates porphyritic. More Letters of Charles Darwin — Volume 1 After passing for a few miles over the coast granitic series, we come to the porphyritic conglomerate, with its usual characters, and with some of the beds distinctly displaying their mechanical origin. Geological Observations on South America In the more northern parts of Chile, this porphyritic series extends over large tracts of country far from the Cordillera; and even in Central Chile such occasionally occur in outlying positions. Geological Observations on South America The lavas are feldspathic, and of porphyritic structure, and, according to the same authority, of an aggregate thickness of 2500 feet. The Student's Elements of Geology As the valley here runs in a very southerly course, the width of the porphyritic conglomerate formation is quite conjectural; and from the same cause, I was unable to make out much about the stratification. Geological Observations on South America The porphyritic conglomerate being purple or reddish, even when alternating with dusty- coloured or bright green porphyries and amygdaloids, is probably an analogous circumstance to the scoriae of the blackish basalts being often bright red. Geological Observations on South America The surrounding lofty mountains appear to be entirely composed of the porphyritic conglomerate, and I estimated its thickness here at between six and seven thousand feet. Geological Observations on South America The strata are inclined, as before stated, from 20 to 30 degrees eastward, towards an irregular north and south chain of andesitic porphyry and of porphyritic greenstone, where they are abruptly cut off. Geological Observations on South America Thus trachyte is usually porphyritic; for in it, as in many modern lavas, there are crystals of feldspar; but in some porphyries the crystals are of augite, olivine, or other minerals. The Student's Elements of Geology The prevailing rock is a purplish or greenish, porphyritic claystone conglomerate. Geological Observations on South America Several strata of purplish porphyritic conglomerate, of no very great thickness, rest conformably upon the feldspathic slate. Geological Observations on South America Some of the varieties appear gradually to become porphyritic with feldspar; and all of them are easily fusible into pale or dark-coloured beads, strongly attracted by the magnet. Geological Observations on South America One of these hillocks of porphyry was capped by some stratified porphyritic conglomerate, which must have been brought up from below, through the whole immense thickness of the overlying gypseous formation. Geological Observations on South America Higher up in the Cordillera there appeared to be a line of andesitic rocks; and beyond them, a fourth escarpment of the porphyritic conglomerate, again dipping eastwards or inwards. Geological Observations on South America The andesite is covered by strata of dark-coloured, crystalline, obscurely porphyritic rocks, and above them by the ordinary porphyritic conglomerates,—the strata all dipping away at a small angle from the underlying mass. Geological Observations on South America In one instance, near Cauquenes, I noticed that a porphyritic conglomerate assumed a spheroidal structure, and tended to become columnar. Geological Observations on South America In proceeding to the mines of Arqueros, the strata of porphyritic conglomerate are at first nearly horizontal, an unusual circumstance, and afterwards they dip gently to S.S.E. Geological Observations on South America These fossils seem to occupy nearly the same position with those at the Puente del Inca,—namely, at the top of the porphyritic conglomerate, and at the base of the gypseous formation. Geological Observations on South America Proceeding up the valley we come to another north and south line of granite, andesite, and blackish porphyry, which seem to lie in an irregular trough of the porphyritic conglomerate. Geological Observations on South America Firstly: above the porphyritic conglomerate formation, there is a fine- grained, red, crystalline sandstone. Geological Observations on South America In the valley of Guasco, an escarpment of porphyritic conglomerate is first seen high up the valley, about two leagues eastward of the town of Ballenar. Geological Observations on South America Above this conglomerate, there is a black siliceous claystone, and above it numerous alternations of dark-purplish and green porphyries, which may be considered as the uppermost limit of the porphyritic conglomerate formation. Geological Observations on South America Differently from what we have seen throughout Chile, the coast here is formed not by the granitic series, but by an escarpment of the porphyritic conglomerate formation, between two and three thousand feet in height. Geological Observations on South America I believe this last great bed is covered by other nearly similar alternations; but the section is here obscured by a tilt from the next porphyritic chain, presently to be described. Geological Observations on South America The gypseous formation, like that of the porphyritic breccia- conglomerate on which it rests, is of inconsiderable breadth; though of greater breadth in Northern than in Central Chile. Geological Observations on South America Proceeding in a north-by-east direction to the village of Combarbala, we come to a third escarpment of the porphyritic conglomerate, dipping eastwards, and forming the outer range of the main Cordillera. Geological Observations on South America On the surface we have the porphyritic gravel, and on it sand with recent shells. Geological Observations on South America |
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