Rocks Exam 11/6/23 Flashcards
extrusive rocks
Igneous rocks that form on the Earth’s surface, these rocks are formed by lava and cool and solidify quickly.
intrusive rocks
Igneous rocks that form deep inside Earth’s crust, formed by Magma, take long to cool and solidify.
Plutonic
another term for intrusive igneous rocks
Extrusion
the formation and process of lava leaving the volcanoes and forming extrusive rocks
magma
lava inside Earth’s crust, much hotter than lava, forms intrusive igneous rocks
lava
Magma that left the Earth’s crust and is on the Earth’s surface, less hotter than magma, forms extrusive igneous rocks
vesicular
gas holes, when extrusive igneous rocks cool quickly and traps gas bubbles
texture
coarse, fine, very coarse, glassy, vesicular, non-vesicular
crystallization
crystallization occurs when an intrusive rock takes long to cool and solidify
sedimentary rocks
rocks formed from the compaction and cementation of sediments
lithification
a process in which sediments are compacted under pressure and cemented together
what are the three types of sedimentary rocks?
clastic, crystalline, bioclastic/organic
clastic sedimentary rocks
formed from the compaction and cementation of sediments
crystalline sedimentary rocks
formed from mineral grains and crystals that precipitate out of solution and evaporate
bioclastic/organic sedimentary rocks
formed from the remains of plants and animals that are compacted and cemented together
how does compaction of a sedimentary rock occur?
when the weight of overlying sediments compress together
how does the cementation of a sedimentary rock occur?
when dissolved minerals precipitate in the pores and glue the minerals together
precipitation
to become a solid out of a solution
fossils
the remains, impressions of former life that has been preserved in sedimentary rocks
ripple marks
formed from waves on the sand before lithification occurred, looks like wavy sand
mud cracks
developed from deposits of wet dry clay that cracked, these cracks are often filled
metamorphic rocks
formed from existing bedrock and is changed by heat and/or pressure, and chemical action within the earth’s crust
what are the two types of metamorphism?
regional metamorphism, and contact metamorphism
what are the two types of foliation?
mineral alignment, and banding
regional metamorphism
rocks that are transformed over a wide geographic area, usually between mountains, and are transformed by the movement of continental crusts. Immense pressure and some heat forms transforms the pre-existing rock into a regional metamorphic rock. regional metamorphic rocks look distorted/deformed mostly due to the pressure and some heat.
contact metamorphism
Pre-existing rock come into contact with intense heat, these rocks come into contact with liquid magma (that’s why it’s called contact metamorphism), the liquid magma burns/bakes the rock and it becomes a metamorphic rock. Contact metamorphism is all about heat, no pressure!
foliation
the repetitive alignment or banding of minerals due to intense pressure, under pressure and heat some minerals may re-crystallize as new minerals or larger crystals
mineral alignment
during foliation, intense pressures may cause minerals to align themselves in distorted layers of mineral crystals that look like repetitive sheets
banding
during foliation, intense pressures may arrange the minerals of a rock to arrange in alternating bands of light and dark minerals, this is called banding.
what does high-grade metamorphism cause?
more heat and pressure cause higher-grade metamorphism which causes an increase in distortion and deformity in metamorphic rocks
what does low-grade metamorphism cause?
low heat and pressure cause low-grade metamorphism which causes little changes in the mineralogy and texture of metamorphic rock, the rock will have little distortion and deformity.
