The truth is out there. (Letters)."Patterns from Nowhere" (SN: 5/17/03, p. 314) was very interesting. While hiking in terrains ranging from midwestern prairies to alpine environments, I've seen different forms of buckling due to freezing forces. Though evaporation was given a nod in the article, it too can be a significant force to form patterned ground Patterned ground is a term used to describe the distinct, and often symmetrical geometric shapes formed by ground material in periglacial regions. Typically found in remote regions of the Arctic, Antarctica, and the Australian outback, but also found anywhere that freezing and . In March of 2009, I walked out to the middle of Death Valley at Badwater, the lowest point in the continental United States United States territory, including the adjacent territorial waters, located within North America between Canada and Mexico. Also called CONUS. . There were polygonal regions throughout the surface as it changed from regular soil of high salt content to pure salt. The polygons typically were 3 to 5 feet across. DEREK WALLENTINSEN, SAN PEDRO, CALIF. The article states that the "concentration of radioactive helium-3 isotopes" in rocks suggests information about the history of the rocks. Insofar in·so·far adv. To such an extent. Adv. 1. insofar - to the degree or extent that; "insofar as it can be ascertained, the horse lung is comparable to that of man"; "so far as it is reasonably practical he should practice as I know, there is only one isotope of helium-3, and it isn't radioactive. DONALD A. NEEPER, LOS ALAMOS, N.M. The helium-3 isotope indeed isn't radioactive, but it is cosmogenic cos·mo·gen·ic adj. Produced by cosmic rays. [cosm(ic ray) + -genic.] Adj. 1. . That is, it's produced when the rock is exposed at Earth's surface and bombarded with natural cosmic rays cosmic rays, charged particles moving at nearly the speed of light reaching the earth from outer space. Primary cosmic rays consist mostly of protons (nuclei of hydrogen atoms), some alpha particles (helium nuclei), and lesser amounts of nuclei of carbon, nitrogen, and so carries information about a rock's history.--S. PERKINS |
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