Thayer Expedition: Scientific Results of a Journey in BrazilFields, Osgood, 1870 - 620 sider |
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Abrolhos abundant appears Bahia banks Barra basin beach beds bluffs bordering Botocudos boulders Brazil Cachoeira Calháo campos Cape Frio catinga channel chapada clay color composed coral covered cretaceous decomposed decomposition deposits described distance drift extends fazenda forest fossils Francisco Geological gneiss gneiss hills gold granite height irregular island Jequitinhonha Lagoa lands leagues limestone Maceió masses Matheos mica miles Minas Geraes Minas Novas Morro mountain mouth Mucury narrow navigation Neu Wied northward observed occur Parahyba Pardo Paulo pebbles Pedra Pernambuco plain Porto Seguro Professor Agassiz province quartz reef region ridge Rio das Velhas Rio de Contas river rock rounded sand sandstone Santa Santo São Francisco São Paulo says seen Serra Serra do Mar shale shallow shore side slate slopes soil southward species specimens Spix and Martius stream surface tertiary thick valley vegetation veins vicinity Villa wooded
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Side 535 - The floor rock at Cocaes is fine micaceous peroxide of iron (specular iron), thin and tabular Much of the jacutinga is foliated It shows great differences of consistency ; some of it is hard and compact as haematite, and this must be stamped like quartz. In parts it feels soapy and greasy, not harder than fuller's earth ; it is easily wetted and pulverized, but it is hard to dry.
Side 208 - ... -08 of an inch above the general surface ; septa in three complete cycles, narrow, thin, subequal, the summits considerably projecting, angular, acute, the inner edges nearly perpendicular, finely toothed, often with a distinct paliform tooth at the base. Columella well developed, of loose open tissue.
Side 469 - Everywhere in the ridges encireling these depressions the loose materials and large boulders were so accumulated and imbedded in clay or sand that their morainic character is unmistakable. Occasionally, where a ledge of the underlying rock crops out, in places where the drift has been removed by denudation, the difference between the moraine and the rock decomposed in place is recognized at once. It is equally easy to distinguish the boulders which here and there have rolled down from the mountain...
Side 199 - Brazilian coast chapeiroes (signifying big hats). At the top these are usually very irregular, and sometimes spread out like mushrooms, or, as the fishermen say, like umbrellas. Some of these cha/peiroes are only a few feet in diameter. A few miles to the eastward of the Abrolhos is an area, with a length of nine to ten and in some places a breadth of four miles, over which these structures grow abundantly, forming the well known Parcel dos Abrolhos, on which so many vessels have been wrecked.
Side 470 - When the lateral moraine turns toward the foot of the ancient glacier, near the point at which the brook of Pacatuba cuts through the former, and a little to the west of the brook, there are colossal boulders leaning against the moraine, from the summit of which they have probably rolled down. Near the cemetery the front moraine consists almost entirely of small quartz pebbles ; there are, however, a few large blocks among them.
Side 540 - The composition of what is called " pure ore " may be taken at about 43 per cent silica, and 57 per cent pyritous matter. Of these minerals, arsenical pyrites is usually the most auriferous, although it does not occur in large quantities. Pure specimens of this substance afford, by assay, from four to six ounces of gold per ton, and wherever crystals of this mineral make their appearance the yield of the precious metal is large. Cubical pyrites is of more frequent occurrence, but is far...
Side 315 - These holes must have been excavated by falling water. There is only one suggestion that I can make as to their origin, and that is that they were formed by glacial waterfalls, in the same way as the pot-holes found over the glaciated regions of North America, as, for instance, in New Brunswick and Nova Scotia, where I have had an opportunity of examining them. It is well known that glacial waterfalls, notwithstanding the constant movement of the ice, are very often stationary, and in the Alps they...
Side 550 - ... north, was doubtless an island at the opening of the palaeozoic time. The highlands' of Brazil formed another island, while the Chiquitos gneiss region to the southwestward was probably another. Since the foregoing was written and sent to the printer, I have been honored by a visit from Dr. T. Sterry Hunt, who has examined with care the large suite of metamorphic rocks I brought home from Brazil. Dr. Hunt has kindly furnished me with the following note for publication : — with red orthoclase...
Side 11 - ... Travellers all speak of the romantic beauty of this spot, and it is worthy of their praise ; for though clothed in the warm verdure of the tropics , it is really Swiss-like in the character of its scenery. If the geologist has any soul, any love for the beautiful, there is no scene which, with all his cold analysis of topographical and geological elements, is more likely to impress him as an artist's work. I know of no view which has affected me so much — not only as a scientific observer,...
Side 35 - Coutmho, placed in my hands by Professor Agassiz, I should, infer that Dr. Capanema is a disbeliever in the glacial origin of the surface deposits claimed by Professor Agassiz and myself to be drift, and that he rather considers them to be the result of decomposition alone. between Rio and Cape Frio. They are composed of gneiss in beds of unequal hardness, and a most excellent opportunity is afforded for the comparison of glaciated rock surfaces and surfaces denuded by subaerial decomposition, or...