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Browse more than 160,000 publications authored by our scientists over the past 100+ year history of the USGS.  Publications available are: USGS-authored journal articles, series reports, book chapters, other government publications, and more.

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Reactivity of clay minerals with acids and alkalies

One-g samples of a montmorillonite, a metabentonite, an illite, two kaolinites, and three halloysites were treated with 50 ml of hydrochloric acid (6⋅45 N, 1:1), acetic acid (4⋅5 N, 1:3), sodium hydroxide (2⋅8 N), sodium chloride solution (pH 6⋅10; Na = 35‰; Cl = 21⋅5‰), and natural sea water (pH 7⋅85; Na = 35⋅5‰; Cl = 21⋅ 5‰) for a 10-day period in stoppered plastic vials. The supernatant solutio

Brucite identified as crystallizing from a natural cold alkaline spring gel

This note presents evidence for the natural low temperature crystallization of brucite, and also indicates the possibility of ambient temperature serpentinization.

Evolving subduction zones in the Western United States, as interpreted from igneous rocks

Variations in the ratio of K2O to SiO4 in andesitic rocks suggest early and middle Cenozoic subduction beneath the western United States along two subparallel imbricate zones dipping about 20 degrees eastward. The western zone emerged at the continental margin, but the eastern zone was entirely beneath the continental plate. Mesozoic subduction apparently occurred along a single steeper zone.

Geologic setting of the apollo 14 samples

The apollo 14 lunar module landed in a region of the lunar highlands that is part of a widespread blanket of ejecta surrounding the Mare Imbrium basin. Samples were collected from the regolith developed on a nearly level plain, a ridge 100 meters high, and a blacky ejecta deposit around a young crater. Large boulders in the vicinity of the landing site are coherent fragmental rocks as are some of

Eocene volcanism and the origin of horizon A

A series of closely time-equivalent deposits that correlate with seismic reflector horizon A exists along the coast of eastern North America. These sediments of Late-Early to Early-Middle Eocene age contain an authigenic mineral suite indicative of the alteration of volcanic glass. A volcanic origin for these siliceous deposits onshore is consistent with a volcanic origin for the cherts of horizon

Genetic implications of the shapes of martian and lunar craters

Craters on Mars and the Moon are alike in that larger craters differ in shape from smaller ones, and older craters differ in shape from younger ones. Smoothed depth-diameter curves for 41 large martian craters photographed by Mariner IV inflect at a crater diameter of 10–20km in a manner similar to curves for lunar craters. Below 10–20km, both depth-diameter curves are linear with a slope of rough

Obsidian hydration dating applied to dating of basaltic volcanic activity

Basalt flows and bombs that contain remelted rhyolite glass can be dated by obsidian hydration dating.

A test of the 40Ar/39Ar age spectrum technique on some terrestrial materials

40Ar/39Ar age spectra were determined for 10 terrestrial rock and mineral samples whose geologic history is known from independent evidence. The spectra for six mineral and whole rock samples, including biotite, feldspar, hornblende, muscovite, and granodiorite, that have experienced post-crystallization heating did not reveal the age of crystallization in any obvious way. Minima in the spectra, h

Pacific geomagnetic secular variation

A smooth field over the central Pacific for a million years indicates a nonuniform lower mantle of the earth.

Lunar Apennine-Hadley region: Geological implications of earth-based radar and infrared measurements

Recently completed high-resolution radar maps of the moon contain information on the decimeter-scale structure of the surface. When this information is combined with eclipse thermal-enhancement data and with high-resolution Lunar Orbiter photography, the surface morphology is revealed in some detail. A geological history for certain features and subareas can be developed, which provides one possib

Lunar metallic particle ("mini-moon"): An interpretation

A troilite-rich nickel-iron particle ("mini-moon") recovered from the moon may be a mound detached from a sphere of silicate glass. Erosion and pitting of the particle may have been caused by passage through a cloud of hot gas and particulate matter formed by meteorite impact on the lunar surface. This explanation is in contrast to the theory that the particle was meteoritically derived molten mat

Sea level as affected by river runoff, Eastern United States

Variations in annual river inflow account for 7 to 21 percent of the total variation in average annual sea level along the Atlantic and Gulf of Mexico coasts of the United States. This compares with 29 to 68 percent of the total variation that can be attributed to the secular rise of sea level, and with 10 to 50 percent of the variation that cannot be attributed to either the river inflow or the s