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The Central Felsic Complex (CFC), centers on Green Mountain and Middleton Ridge and is older than the Eastern Felsic Complex. Here, ash is typically welded together and breccia is laden with rhyolite and obsidian fragments. Middleton Ridge formed more than one million years ago and is accompanied trachyte and rhyolite flows.
A Btry. lost a 1 gun chief from mortar fragments and several others badly wounded, including Sgt. John Thomas, 1st section Gun Chief. The 3rd Battalion, 82nd Artillery continued support in the area until April, 1971 when the battalion transitioned north to defend Da Nang and bases south of the DMZ.
Rimrock Draw Rockshelter is a rockshelter located in Eastern Oregon of the US. It is an archaeological site being studied by the University of Oregon under the guidance of Dr. Patrick O'Grady in coordination with the Museum of Natural and Cultural History [1] and in partnership with the Bureau of Land Management (BLM).
Obsidian (/ ə b ˈ s ɪ d i. ən, ɒ b-/ əb-SID-ee-ən ob-) [5] is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth.
The presence or absence of an obsidian hydration band has been used to distinguish prehistoric obsidian debitage from obsidian debitage produced by modern flintknappers. This distinction can be made because it takes about 70 years for a band to enlarge sufficiently so that it is readily detectable on a freshly flaked surface of a piece of obsidian.
Tephra fragments are classified by size: Ash – particles smaller than 2 mm (0.08 inches) in diameter; Lapilli or volcanic cinders – between 2 and 64 mm (0.08 and 2.5 inches) in diameter; Volcanic bombs or volcanic blocks – larger than 64 mm (2.5 inches) in diameter
Obsidian projectile point.. Obsidian is a naturally formed volcanic glass that was an important part of the material culture of Pre-Columbian Mesoamerica.Obsidian was a highly integrated part of daily and ritual life, and its widespread and varied use may be a significant contributor to Mesoamerica's lack of metallurgy.
Mono Paiutes gathered obsidian from the Mono–Inyo Craters to make sharp tools and arrow points. [38] Unworked obsidian was carried by the Mono Paiutes over passes in the Sierra Nevada to trade with other Native American groups. Chips of Mono–Inyo obsidian can still be found at many ancient mountain campsites. [39]