University of California Publications. Bulletin of the Department of Geological Sciences, Volume 1University of California Press, 1896 |
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abundant acid actinolite albite altitude amphibole analcite Angel Island appears areas augite basalt beds blue amphibole California cañons Carmelo changes character chemical chert cleavage cliff Coast Ranges color colorless critical periods crust crystals Cuyamas delta deposition described diabase dike dyke elevation eruptive rock evidence extinction angle facies feet feldspar formation forms fourchite fragments Geol geological glaucophane grains granite granular green groundmass hornblende iddingsite idiomorphic inclusions intrusive irregular isostasy latter lawsonite magma magnetite mass matrix metamorphism microscope miles mineral Miocene mountain nepheline numerous observed occurs olivine optical original orogenic orthoclase parallel peneplain petrographical phenocrysts plagioclase plane Plate pleochroism Pliocene Point portion present prismatic prisms probably pyroxene quartz radiolarian ridge River San Clemente San Francisco San Pedro Hill sandstone Santa schist sea-cliffs secondary sediments serpentine shale shore shown shows slides slope spheroidal basalt strata stream structure subsidence surface terraces thickness tion topography twinning uplift valley writer
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Page 100 - The garnet occurs as crystals, mostly imperfectly developed, known locally as "pockets." These crysManuscript received at the office of the Institute Nov. 30, 1942. * Manager. Barton Mines Corporation, North Creek, NY tals vary in size from a fraction of an inch to a foot or more in diameter.
Page 390 - Hence we infer that isostasy is competent only on the supposition that it is kept in action by some other cause tending constantly to disturb the equilibrium which would otherwise result. Such a cause is found in secular contraction, and it is not improbable that these two seemingly divergent theories are really supplementary.
Page 365 - California lies, as is well known, between the two dominant mountain chains of the state, — the Sierra Nevada on the east and the Coast Ranges on the west. It...
Page 233 - Californian radiolaria is the number and variety of forms of the genus Dictyomitra present in it, and it is not without significance that this genus is also abundantly represented in the Jurassic and Cretaceous radiolarian jaspers and cherts mentioned above. No other microscopic organisms besides radiolaria can be seen in the Angel Island or in the Buri-buri beds. It is quite possible that diatoms may have been intermingled with radiolaria in these deposits, but the fossilization, which has been...
Page 113 - They are, however, of sufficient importance and immediate interest in the judgment of the writer to warrant present publication, notwithstanding the many gaps which could readily be filled by more systematic inquiry. Even with these gaps, the information here given establishes two general facts of no small moment in certain discussions affecting the recent history of the continent. These are: — 1. The uplift or emergence from the sea of the...
Page 394 - These results tend to show that the earth is able to bear on its surface greater loads than American geologists, myself included, have been disposed to admit. They indicate that unloading and loading through degradation and deposition can not be the cause of the continued rising of mountain ridges with reference to adjacent valleys, but that, on the contrary, the rising of the mountain ridges, or orogenic corrugation, is directly opposed by gravity, and is accomplished by independent forces in spite...
Page 193 - Island, appears to indicate that "radiolarian chert" is, on the whole, a better designation for them, inasmuch as it casts some light upon their origin, and suggests their relationship with similar cherts in Europe. The lessons to be drawn from these facts are that the jasper in its essential character is not a metamorphic rock, and that it was formed of siliceous sediments resulting in great measure from organic life, as has been demonstrated to be the case with similar rocks in other parts of the...
Page 21 - The infusorial beds at Monterey appear, therefore, to be exceptional and not representative of the series as a whole. Moreover, it becomes probable from a microscopic examination that the mass of the white chalky shale, in part at least, is the fine ash of a very acid volcanic eruption.
Page 379 - ... has affected the region of San Francisco Bay.f It will be seen from the foregoing, that up to the beginning of the Pleistocene, the area now occupied by the Great Valley was at no time the theater of particularly heavy sedimentation or active subsidence. There is evidence that during the Cretaceous and Miocene the heaviest sediments and deepest depressions lay to the * Loc. cit., pp. 158, 159. t Ibid, p. 265. west of the present valley, and along the line now occupied by the Coast Ranges.
Page 9 - Lucia granite, parallel to basal pinacoid (ooi), showing inclusions of quartz, q; feldspar, f; biotite, b; and muscovite, m. All the quartzes have a common orientation, with the optic axis perpendicular to the basal pinacoid of the host; and the feldspars have a common orientation by groups, x 8. planes but each mineral has a common orientation for distinctly isolated individuals widely scattered through their host. Thus, for a considerable area, all...