GLOSSARY – T-U-V
by: Charles O’Dale
Russian term for IMPACT MELT ROCK.
Area and rocks exposed to the impacting projectile, sometimes called country rock.
Natural, silica-rich, homogeneous glasses produced by complete melting and dispersed as aerodynamically shaped droplets during terrestrial impact events. The process of tektite formation is disputed, but many researchers believe that they are formed in the early contact and compression stage of impact cratering. Most tektites are high in silica (68-82%) and very low in water content (average 0.005%): their composition is unlike that of obsidian and more like that of shale. They range in color from black or dark brown to gray or green.
Tektites have been found in “strewn fields” on the Earth’s surface.
|Tektite Strewn Field||Age (Ma)||Crater Source|
|Darwin Glass||0.816 ± .007||Darwin Crater, Tasmania|
|Libyan Desert Glass||26||North Africa|
|Ivory Coast||1.07||Bosumtwi, Ghana|
|European “moldavite”||15||Ries, Germany|
|North American||35.5||Chesapeake, Virginia|
|PARTICLE NAME||PARTICLE SIZE|
|Volcanic Ash||<2 mm|
|Volcanic Dust||<0.063 mm|
“Tephra” and “pyroclastics” are general terms used in reference to particles of igneous rock material of various sizes that have been ejected from volcanoes. They are classified by size. The terms “ash” and “dust” communicate a specific size of tephra or pyroclastic particles. These are summarized in the table above.
TIMELINE (on earth)
A group of chemical elements and chemical compounds with low boiling points that are associated with a planet’s or moon’s crust or atmosphere. Examples include nitrogen, water, carbon dioxide, ammonia, hydrogen, methane and sulfur dioxide.
[see – REFRACTORY]