Igneous Structures and Field Relations-CH4

Image source winter 2010 21 7 8272012 landforms lava

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Unformatted text preview: sified based on their surface forms i. Pahoehoe (ropv) = flow with smooth or filamented Pahoehoe lava flows from Kilauea (October, 1999) folds due to continued flow beneath a glassy surface ii. Aa - flow with jagged, rough surface; forms from more viscous lava that has lost its gas content. very Aa and Pahoehoe flows Image source: Hawaiian Volcano Observatory website: http://wwwhvo.wr.usgs.gov/kilauea/ ] 22 Landforms – lava flows Lava flows from Kilauea Volcano, HI. Image source: Hawaiian Volcano Observatory website: http://wwwhvo.wr.usgs.gov/kilauea/ ] sharp iii. flows often have pahoehoe 23 Landforms – lava flows Image source: Hawaiian Volcano Observatory website: http://wwwhvo.wr.usgs.gov/kilauea/ ] 24 8 8/27/2012 Landforms – lava flows iv. Lava tube - long tubular opening in which lava on outside has solidified but in center it has drained out image from the Hawaiian Volcano Observatory website: http://wwwhvo.wr.usgs.gov/kilauea/ Skylight sin lava tube from Puu Oo Eruption of Kilauea Volcano in Hawaii, HI. [photo by Jim Kauahikaua] Lava tube in the Galapagos Islands (Ecuador). Note the 25 lava flow lines. [Photo:. Barb Dutrow - LSU] Landforms – lava flows Basaltic flows are classified based on their surface forms: v. Columnar joints - ca. 5-6 sided pillars, produced by 26 Landforms – lava flows slow cooling magma Basaltic flows are classified based on their surface forms: vi. Pillow lavas - piles of elliptical, sac-like bodies (ca. 1m) that form when lava solidifies underwater characterized by glassy rind, commonly vesicular Contact between deposits of pillow lava (left), and tephra (right, orange), near Aci Castello, Sicily. Note person at lower left for scale (photo M. Fulle). (was gas charged) with crystalline interior Inset: Diver examines recently extruded lava pillow off the coast of Kilauea volcano, Hawaii (photo R.D. Grigg). 27 9 8/27/2012 Landforms – lava flows Rhyolitic lavas erupt at 800-1000 C, very viscous form steep-sided, bulbous deposits Newberry Crater, Oregon. • Central pumice cone (~6,600 BP) is in left-center. Big Obsidian flo...
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