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Topo

Rock Formations

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Topo

Ecoregions

Public Lands

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Challis intrusive rocks. (IDTei;0)

Geologic Formation in ID, MT

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Lithology

Syenite

Rhyolite

Diorite

Other (6,933 mi²)

Geologic Age

Ypresian – Lutetian (49 Ma – 43 Ma ago)

Geologic Unit Label

Tei

Shallow roots of Challis volcanic field. Older suite of granodiorite and quartz monzodiorite and subordinate diorite, granite, and subvolcanic dacite; includes Jackson Peak, Beaver Creek, Marsh Creek, and Summit Creek stocks (49-45 Ma). Younger suite of granite and minor syenite and subvolcanic rhyolite; includes Sawtooth, Casto, Bungalow, and Lolo Hot Springs plutons (47-43 Ma). (Eocene Challis Magmatic Complex and Related Sedimentary Rocks).

— USGS

Taxonomy

Classified As

Geologic Formation