Bulletin of the Department of Geology of the University of CaliforniaThe University, 1896 - 362 pages |
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abundant actinolite altitude amphibole analcite Angel Island appears augite basalt beds blue amphibole California cañons Carmelo Bay carmeloïte character chemical chert cleavage cliff Coast Ranges color crystals delta deposition described diabase dike dyke elevation erosion eruptive rock evidence facies fact feet feldspar formation forms fourchite fragments Geol geological glaucophane grains granite granular gravels green ground-mass hornblende iddingsite idiomorphic inclusions intrusive irregular isostasy isostatic latter lava Lawson lawsonite magma magnetite mass microscope miles mineral Miocene mountain movements nepheline numerous observed occurs olivine optical original orogenic orthoclase parallel peneplain petrographical phenocrysts plagioclase plane Plate pleochroism Pliocene Point porphyritic portion present prismatic prisms probably pyroxene quartz radiolarian ridge River San Francisco San Pedro Hill sandstone Santa Lucia schist sea-cliffs sections sediments serpentine shale shore shown side Sierra silica slides slope spheroidal basalt spherulitic strata stream structure subsidence surface terraces thickness tion topography uplift valley writer
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Page 397 - ... denser or lighter than others, its normal figure would no longer be spheroidal. Where the lighter matter was accumulated there would be a tendency to bulge, and where the denser matter existed there would be a tendency to flatten or depress the surface. For this condition of equilibrium of figure, to which gravitation tends to reduce a planetary body, irrespective of whether it be homogeneous or not, I propose the name isostasy.
Page 104 - 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 238 - Hinde,137 who wrote : 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 sufficient to obliterate most of the radiolarian structure, would completely destroy all traces of the smaller and more delicate diatoms.
Page 199 - 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 397 - Moreover, isostasy does not seem to meet the requirements of geological continuity, for it tends rapidly towards stable equilibrium, and the crust ought therefore to reach a state of repose early in geologic time. But there is no evidence that such a state has been attained...
Page 242 - The progressive uplift of this peneplain, with its residual monadnocks, to an elevation for the plain of from 1,600 to 2,100 feet above the sea level, the adjacent mountainous tracts participating in the same movement. 5. The advance in the new geomorphic cycle to a stage of late adolescence or early maturity. 6. A very recent local sag or depression of about 100 miles of the coast adjacent to the Golden Gate, and the consequent flooding of the stream valleys by the ocean.
Page 363 - Castorid;e 369 OCCURRENCE. THE fossil rodent remains here described and referred to the Castoridae or beaver family, were found by the writer, about two years ago, near Bald Peak, two miles east of Berkeley. The freshwater beds in which they were found form part of a very thick series of gravels, clays, limestones, and eruptives belonging, according to Prof. AC Lawson, to the lower division of the Pliocene.* At the point where the rodent bones were found, the clays contain abundant but fragmentary...
Page 369 - In the following table, giving the geological distribution of most of the known Castoroid species, the American Castoridae seem to reach their maximum development at or before the beginning of Pliocene time. If the culmination of the group in Eurasia can be definitely located at all, it would seem to occur in the Pliocene, or somewhat later than in America. This seems the more probable, as the genus Steneofiber lived longer in Europe than in America, while of the three related genera, Eucastor, Sigmogomphius,...
Page 25 - 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 11 - 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...