The density and mass distribution of meteoritic bodies in the neighborhood of the Earth's orbit

Abstract

Abstract. A study of the frequency of meteorite falls in areas which have been highly populated throughout the last century indicates that the average rate of fall of meteorites on the earth probably lies between 0.32 and 1.0 falls/year 10 • km •. The frequency of fall as a function of type and mass has been studied, and it is shown that the distribution curves for stones and irons have similar shapes. The curves are also remarkably similar to those observed for asteroids. The observed relationships are used to calculate the impact frequency of meteoritic particles upon the earth and moon as a function of their size.

Fossils of Hydrothermal Vent Worms from Cretaceous Sulfide Ores of the Samail Ophiolite, Oman

“…The circulating seawater is modified by heat and reaction with the basaltic host rock into 17 an oxygen-depleted acidic solution enriched in transition metals and hydrogen sulfide (7,8). When solutions of this composition vent onto the sea floor, a suite of sulfide minerals rich in iron, zinc, and copper is deposited locally (2,3,(9)(10)(11)(12). The reduced sulfur in the outflowing hydrothermal solutions is a source of chemical energy for chemolithotrophic bacteria, which apparently constitute the base of a food chain for dense faunal communities clustered around the vents (13)(14)(15)(16).…”

“…Mussels, anemones, barnacles, limpets, siphonophores, and other animals are also present in certain vent areas. Some species of vent worms thrive remarkably close to the escaping hydrothermal fluids, which may have temperatures as high as 350°C (2,8). Sulfide minerals precipitating within the habitats of these worms envelop and preserve the worm tubes in a sulfide matrix.…”

“…These chimneys typically rest on top of SCIENCE, VOL. 223 I basal mounds composed of sulfide-cemented chimney debris (2,9). Samples collected from white smokers and basal mounds contain abundant fossilized tubes of two worm species, the polychaete Alvinella pompejana Desbruyeres (9,21) and the vestimentiferan Riftia pachyptila Jones (22).…”

Addendum:The density and mass distribution of meteoritic bodies in the neighborhood of the Earth's orbit

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In an earlier paper [Brown, 1960], the author estimated the frequency of meteorite impact upon the earth and moon on the basis of the numbers of observed falls over a period of a century in Japan, India, and Western Europe. All of these areas have had high rural population densities during the entire period.

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Meteorite Falls and Finds: Some Statistics

“…The chance of one of these unrecorded falls being found subsequently is extremely small. This paper reviews the statistics of both meteorite falls and meteorite finds, with respect to time, mass and position, and brings up to date the excellent work done, for example, by Mason (1962), Leonard and Sianin (1941) and Brown (1960). Data for the 2310 meteorites listed by Hey (1966) and Hutchison, Bevan and Hall (1977) in the British Museum's Catalogue ofMeteorites and Appendix, respectively, were fed into the University of Sheffield's computer and then sorted according to certain characteristics.…”