James St. John:
Gunflint Chert (Paleoproterozoic, ~1.878 Ga; near Port Arthur, Ontario, Canada) 1
James St. John:
Gunflint Chert (Paleoproterozoic, ~1.878 Ga; near Port Arthur, Ontario, Canada) 2
James St. John:
Fissile chert (Gunflint Formation, Paleoproterozoic, ~1.878 Ga; Ontario, Canada) 1
James St. John:
Fissile chert (Gunflint Formation, Paleoproterozoic, ~1.878 Ga; Ontario, Canada) 2
James St. John:
Fissile chert (Gunflint Formation, Paleoproterozoic, ~1.878 Ga; Ontario, Canada) 3
James St. John:
Fissile chert (Gunflint Formation, Paleoproterozoic, ~1.878 Ga; Ontario, Canada) 4
James St. John:
Fissile chert (Gunflint Formation, Paleoproterozoic, ~1.878 Ga; Ontario, Canada) 5
James St. John:
Fissile chert (Gunflint Formation, Paleoproterozoic, ~1.878 Ga; Ontario, Canada) 6