METAMORPHIC ROCKS Types of Metamorphism Regional Metamorphism Form when heat and/or pressure change existing rock into a new rock through recrystallization Types of Metamorphism Regional Metamorphism occurs over a large area where rocks are buried deeply or are caught in a mountain building event rocks recrystallize due to high T & P Contact Metamorphism occurs when rocks are locally exposed to high temperatures in a small area (e.g. under a lava flow, at a meteorite impact site, etc.)

classified by texture & origin rock / composition METAMORPHIC ROCKS classified by texture & origin rock / composition Texture FOLIATED – layered or banded foliation forms when long mineral crystals line up in response to pressure or when light and dark minerals separate NONFOLIATED – not layered or banded no foliation forms when mineral crystals do not have a long axis and when only a few similar minerals are present

classified by texture & origin rock / composition METAMORPHIC ROCKS classified by texture & origin rock / composition Origin Rock / Composition origin / parent rock → metamorphic rock sandstone → quartzite (nonfoliated) conglomerate → metaconglomerate (nonfloliated) limestone → marble (nonfoliated) shale → slate → schist → gneiss (foliated) granite → schist → gneiss (foliated) basalt → amphibolite OR schist → gneiss (rock names!) (foliated)

http://rst.gsfc.nasa.gov/Sect2/rock_cycle_800x609.jpg

http://www.physicalgeography.net/fundamentals/images/rockscycle.GIF