Geography 1100 Lecture Notes - Lecture 2: Aphanite, Basalt, Phanerite

• School: Western University
• Department: Geography
• Course: Geography 1100
• Professor: D.Kim Holland

Document Summary

Earth sciences 1022b lecture brief 16 jan 14. Igneous (from fire) rocks crystallize from molten silicate material called magma that forms at high temperatures and pressures deep in the earth. Magma rises through the crust and either reaches the surface by volcanoes (extrusive) or cools below surface (intrusive). Magma that reaches the surface is called lava. How magmas evolve: according to norman l. bowen"s (canadian) reaction series, crystals settle in a magma chamber. Igneous composition: from dark (mafic, less silica, more fe, mg) to light (felsic, more silica) minerals. Naming igneous rocks - use rock textures and mineral compositions (dark vs. light: felsic (granitic) rocks (70% silica) granite (found in mountains) and rhyolite(found in volcano); granite is widely used for building stone, monuments, and headstones.