o the largest igneous features; massive intrusive features formed by the joining of
various plutons into one colossal pool of magma; usually felsic (granitic); large
enough to form entire mountain ranges
o typically very large, visco
o composed in part of glass and in part of crystalline material.
o a foreign body enclosed in a crystal or rock. See xenolith.
o a variety of intersertal texture in which the interspaces are filled with gra
Places where three plate boundaries intersect at a point.
1. Volcanic rock forms at spreading centre.
2. Forms graben or rift zones, serve as basins and accumulate sand.
3. Magma intrudes (local metamorpism, l
o a frothy structure in glassy rocks due to extreme vesiculation in the fluid stage by
expanding and escaping gases.
o a peripheral zone of minerals formed around another mineral by reaction of the
latter with the magma or adjacent
o what is sedimentary rock referred to as?
o the process that sediments will generally compact into layers of cement together
by mineral matter
o the result of a sedimentary rock being exposed to even higher amounts
o Rough jagged blocks of hard lava, irregular flow. Extrusive structure.
o A regularly spaced crack that commonly develops in lava flows forming five or
six sided columns. Extrusive structure.
o Lava that cools underwat
o contains mostly elongated and/or granulated crystals (not flat); strong segregation
of light and dark minerals
non-foliated metamorphic rocks
o almost always the result of high-grade metamorphism; crystals interlock instead
of simply lining up
o deposition example of shells of mollusks
o forms from dead mollusks who extract it from the water to create shells (90% of
o unique since it is composed of almost entirely organic matter; accounts fo
o Solid aggregate of mineral grains, or a solid naturally occurring mass composed
of mineral grains, glass, altered organic matter, and a combination of these
o The overall study of rocks.
o The study of the descrip
o applied to igneous rocks with a low silica content (usually less than 52%); the
term mafic is preferred.
o fine grained basaltic intrusive common in dikes also called dolerite (Brit)
o applied to material (Lava) poured out throu