Gems with impact.With respect to the article on kimberlites, diamonds, and mantle fractures ("A Gemstone's Wild Ride," SN: 6/30/07, p. 412), may I suggest that the fractures in question emanate em·a·nate intr. & tr.v. em·a·nat·ed, em·a·nat·ing, em·a·nates To come or send forth, as from a source: light that emanated from a lamp; a stove that emanated a steady heat. from hypervelocity bolide bolide: see fireball. impacts on Earth. There is ample spatial correlation between impact craters formed by oblique impacts with crustal-fracture systems that propagated outward along the direction of impact. GREGORY C. HERMAN, NEW JERSEY GEOLOGICAL SURVEY The term geological survey can be used to describe both the conduct of a survey for geological purposes and an institution holding geological information. A geological survey , TRENTON, N.J. |
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