Return to Geologic Processes page

Geology of Mount Shasta

Figure 5

Return to Mount Shasta home page

Rock type: BASALT BASALTIC ANDESITE ANDESITE DACITE
Wt. % silica: 47 - 52 52 - 57 57 - 63 63 - 72
Olivine
Hypersthene
Augite
Hornblende
Biotite
Plagioclase
Quartz
Magnetite/ilmenite
Figure 5: Classification chart for volcanic rocks found in the Mount Shasta area. Silica contents and typical phenocryst assemblages (shown by colored bars) are given for each rock type. Hand-sample and thin-section photographs of a sample of each rock are linked to its name at the top of the column.
 

Geology ~ Environment ~ Native Americans ~ Folklore ~ History ~ Art ~ Literature
Recreation ~ Maps ~ Mount Shasta Collection ~ Bibliography ~ Lesson Plans ~ About Project