WHAT TO KNOW LIST, GEOLOGY 100
EXAM II, WEDNESDAY, MARCH 2
Exam II will cover the following topics.
If a particular topic is not covered or only partially covered
in class, you are responsible for learning about it by doing the reading assignments in the textbook.
a topic is NOT listed here, IT WILL NOT BE ON THE TEST!
Geothermal gradient: The rate temp. increases with depth in the earth.
Partial melting: Some rock melts, some doesn’t, different melting points of the minerals
Variables affecting melting – pressure (decompression melting), addition of volatiles (water), heat transfer
Igneous textural terms – phaneritic, aphanitic, phenocrysts, porphyry, pegmatite, volcanic glass (obsidian): Phaneritic:
Minerals cooled slowly & had time to grow; visible minerals. Aphanitic: cooled quickly, very fin grained. Porphyry:
magma cools slowly causing minerals to grow & magma erupts, bringing crystallized minerals with it. Pegmatite:
very coarse grained. Obsidian: Glassy Rock
Chemically equivalent intrusive & extrusive igneous rock types – peridotite & komatiite, gabbro & basalt, diorite &
Magma compositions (ultramafic, mafic, intermediate, silicic) and characteristics: Ultramafic: very low silica. Mafic:
Low silica. Intermediate: Intermediate silica. Silicic: High silica
Fractional crystallization: when magma changes as it cools
Bowen’s reaction series: Minerals stick together by crystallizing temps.
Magmatic mineral deposits - Layered igneous intrusions, pegmatites, granites:
Intrusive rock bodies – pluton, batholith, sill, dike
Volcano types – shield, composite, cinder cone