Category:Rocks in Montana by geochronology

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Precambrian	Phanerozoic rocks in Montana
Preceded by Proterozoic Eon	Phanerozoic rocks in Montana
	Paleozoic Era						Mesozoic Era			Cenozoic Era
	Cambrian	Ordovician	Silurian	Devonian	Carboniferous	Permian	Triassic	Jurassic	Cretaceous	Paleogene	Neogene	4ry

Subcategories

This category has the following 29 subcategories, out of 29 total.