Earth Science Period 3

EROSION

GLACIERS

PLATE TECTONICS

Magmatic consolidation

Crystalline and Non-Crystalline

Non-porous

Stratification

Fossilization

Porosity

Fast cooling on the surface results in many small crystals or quenching to a glass. Gives rise to aphanitic texture (crystals cannot be distinguished with the naked eye), or obsidian (volcanic glass).

Slow cooling at depth in the earth results in fewer much larger crystals, gives rise to phaneritic texture.

Porphyritic texture develops when slow cooling is followed by rapid cooling. Phenocrysts = larger crystals, matrix or groundmass = smaller crystals.