Protogaea Civica I (Franciscan Formation/San Francisco, CA)

Flags depicting the geologic materials and basic structural relationships of Holocene architecture and the Franciscan Formation, San Francisco, CA, from the top:

Reinforced Concrete
Ferruginous Radiolarian Chert
Meta-basalt/Greenstone
Graywacke/Metagraywacke Sandstone
Shale Matrix Melange/Shear Zone
Serpentinite

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project description; notes/credits for SF flags