porphyritic conglomerate

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  • 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. Cited from South American Geology, by Charles Darwin
  • 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. Cited from More Letters of Charles Darwin Volume I
  • 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. Cited from South American Geology, by Charles Darwin
  • Several strata of purplish porphyritic conglomerate, of no very great thickness, rest conformably upon the feldspathic slate. Cited from South American Geology, by Charles Darwin
  • We then come suddenly to the great gypseous formation [B], without having passed over, differently from, in all the sections hitherto described, any of the porphyritic conglomerate. Cited from South American Geology, by Charles Darwin
  • Firstly: above the porphyritic conglomerate formation, there is a fine- grained, red, crystalline sandstone. Cited from South American Geology, by Charles Darwin
  • The altered clay-slate formation, already described, is seen in several parts of the valley as far down as Las Vacas, underlying the porphyritic conglomerate. Cited from South American Geology, by Charles Darwin
  • In one instance, near Cauquenes, I noticed that a porphyritic conglomerate assumed a spheroidal structure, and tended to become columnar. Cited from South American Geology, by Charles Darwin
  • 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. Cited from South American Geology, by Charles Darwin
  • 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. Cited from South American Geology, by Charles Darwin
  • The gentle passage of the feldspathic slate, at Jajuel, into the porphyritic conglomerate, which is certainly of aqueous origin, should also be taken in account. Cited from South American Geology, by Charles Darwin
  • I will describe the section seen on the eastern side of this mountain [D], beginning at the base with the lowest bed visible in the porphyritic conglomerate, and proceeding upwards through the gypseous formation. Cited from South American Geology, by Charles Darwin
  • 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. Cited from South American Geology, by Charles Darwin
  • This mountain of porphyry seems to form a short axis of elevation, for south of the road in its line there is a hill [C] of porphyritic conglomerate with absolutely vertical strata. Cited from South American Geology, by Charles Darwin
  • 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. Cited from South American Geology, by Charles Darwin
  • After leaving the plutonic hills near the town, I met first, as in the main valley, with the gypseous formation, having the same diversified character as before, and soon afterwards with masses of porphyritic conglomerate, about one thousand feet in thickness. Cited from South American Geology, by Charles Darwin
  • 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. Cited from South American Geology, by Charles Darwin
  • The limestone, however, with these fossils here lies at the very base of the formation, just above the porphyritic conglomerate, and certainly several thousand feet lower in the series, than the equivalent, fossiliferous, black, shaly rocks high up on the Peuquenes range. Cited from South American Geology, by Charles Darwin
  • One brick-red porphyry, which above the Jaula forms an isolated mass in the midst of the porphyritic conglomerate formation, and lower down the valley a magnificent group of peaked mountains, differs remarkably from all the other porphyries. Cited from South American Geology, by Charles Darwin
  • The mountains of porphyry eastward of the micaceous schist soon, but gradually, assume (as observed in so many other cases) a stratified structure, and can then be recognised as a part of the porphyritic conglomerate formation. Cited from South American Geology, by Charles Darwin
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