IGNEOUS

• most rocks in the earths crust are igneous in origin
• Formation of Igneous Rocks
• from the solidification of magmas
• temperature, pressure, and water are catalysts of rock melting
• partial melting
• since melted rock (liquid) has a lower density than solid rock, it rises in the earths crust where it accumulates in magma chambers
• Classification based on texture and composition
• Texture: size of individual grains / minerals
• phaneritic vs. aphanitic
• glassy
• porphyritic
• fast cooling = "fine" texture or "glassy"
• slow cooling = "course" texture
• Intrusive Igneous Rock Bodies
• magmas from the melting of mantle crustal rocks
• magmas rise, intrude into the crust
• Extrusive Igneous Rocks
• Lavas - pahoehoe, aa (viscosity)
• Pyroclastics (fire fragments)
• volcanic ash and tuff
• Volcanic Glass (pumice, scoria, obsidian)
• Porphyritic Igneous Rocks
• Volcanism: the process by which magma from the interior of the earth rises through the crust, emerges onto the surface as lava, and cools into volcanic rock
• Anatomy of a volcano (overhead)

• Types of lava (based on silica content)
• felsic, andesitic, mafic
• Types of Volcanic Deposits
• Basaltic: Flood Basalts, Pahoehoe, Aa, Pillow lava
• Rhyolitic
• Andesitic
• Textures: glassy, vesicular
• explosive vs. gentle eruptions
• Pyroclastic Deposits
• Air fall or tephra
• Ejecta: ash, tuffs and breccias, bombs
• Surge:
• nuée ardante (glowing cloud)
• Mudflow
• lahar
• Landforms and Eruptive Styles
• Shield Volcanoes
• gentle eruptions consisting of basaltic lavas
• low silica and low viscosity
• fissure eruptions and flood basalts
• example: Mauna Loa
• Volcanic Domes
• explosive eruptions consisting of felsic volcanism
• high silica and high viscosity
• ash flows
• example: Mount St. Helens (1980)
• Cinder-Cones Volcanoes
• pyroclastic eruptions
• Composite Volcanoes (stratovolcano)
• alternating lava and pyroclastic eruptions
• Craters
• central depression at the summit of most volcanos
• Calderas (collapsed craters)

SEDIMENTARY

Sedimentary rocks cover 75% of the surface of the earth

• Types of Sedimentary Rocks
• Clastic (detrital)- fragments of other rocks
• Non-clastic - chemical precipitates and evaporites
• Formation of Sedimentary Rocks
• Weathering
• Transportation and Sorting
• abrasion
• rounding and sorting
• Deposition
• depositional environments
• Lithification
• compaction
• cementation

METAMORPHIC ROCKS

Metamorphism

process by which rocks undergo changes in mineralogy, texture, or chemical composition

• WHERE? in the crust and mantle

• Metamorphic Agents: internal heat, weight of rock, horizontal pressures of deformation result in:
• temperature
• pressure
• directed
• Types of Metamorphism
• Contact
• plate convergence
• oceanic and continental hot spots
• deformed mountain belts
• Regional
• plate subduction
• plate convergence
• Burial