Transcript Slide 1
And some rin uphill and down dale, Knapping the chucky stones to pieces wi’ hammers, Like sae mony roadmakers run daft – They say it is to see how the warld was made. - Sir Walter Raleigh Of Igneous rocks and volcanoes Webpage for course (daytime) Webpage for course (nighttime) Lecture 1 (Intro) Difference between rocks and minerals Three types of rocks: Minerals in igneous rock Minerals distributed randomly Crystals grow into one another Fig. 3.2 Continental vs. oceanic crust Mineral composition of earth crust Continental crust Oceanic crust Feldspar 58% Chain silicates 13% Quartz 11% Micas (incl. clays)10% Calcite, Gypsum, Halite 3% Olivine 3% Misc. 2% Olivine Chain silicates Plagioclase feldspars 30% 30% 40% Types of Igneous environments Volcanic (extrusive) fine-grained Plutonic (intrusive) coarse-grained Mineral compositions Continental Intermediate Oceanic Volcanic Plutonic Three types of volcanoes due to mineral characteristics Continental Composite Oceanic Three types of volcanoes pyroclastic composite < http://www.clas.ufl.edu/users/pciesiel/ gly3150/mt_st_helens2.gif > < http://upload.wikimedia.org/wikipedia/commons/0/ 06/Mauna_Kea_cinder_cone.jpg > shield History of a volcano obsidian Fig. 3.14b pumice Fig. 3.15a Eroded volcano – volcanic neck Example: Devil’s Tower, Wyoming http://www.destination360.com/northamerica/us/wyoming/devils-tower-nationalmonument Volcanic crater - caldera Example: Crater Lake, Oregon http://www.dustydavis.com/longride/2004 Where do composite volcanoes occur? “Ring of Fire” Fig. 4.33 Unusual volcanoes - kimberlites http://volcano.oregonstate.edu/ book/export/html/170&usg Unusual volcanoes - kimberlites Associated with hotspots Loper and McCartney hypothesis of dinosaur extinction http://www.astro.virginia.edu/class/ocon nell/astr121/marsImages.html&usg