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USGS "blue file" Loc. 13366

Fergus County, Montana
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Next site in MontanaUSGS "blue file" Loc. 13408 · 5 mi

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Based on our latest records, with claims updated from the BLM on Oct 9, 2026. Land and claims can change quickly, so check before you go.

Minerals on record here

1 mineral

Recorded here: fossil.

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5 miUSGS "blue file" Loc. 13408Fossil5 miUSGS "blue file" Loc. 13365Fossil5 miUSGS "blue file" Loc. 13387Fossil

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About USGS "blue file" Loc. 13366

USGS "blue file" Loc. 13366 is a fossil collection site in Fergus, Montana, cataloged in the Paleobiology Database. Fossils here come from the Heath Formation, dated to the Serpukhovian (330.3–323.4 million years ago). The depositional environment is recorded as offshore and the tectonic setting is cratonic basin. Documented finds include Orbiculoidea interlineata, Antiquatonia, Buxtonia, Leiorhynchus, Permophorus, Angyomphalus excavatus.

Geologic setting

Formation
Heath
Geologic interval
Serpukhovian
Age
330.3–323.4 Ma
Depositional environment
offshore
Tectonic setting
cratonic basin
Recorded occurrences
6
Geology notes

Some of the upper Heath MAY be estuarine/non-marine as noted by the author. These localities contain wood and other plant fragments, are non-calcareous and contain no marine fossils. These localities have been omitted by me [MS].

Locality notes

From various horizons in three conspicuous road cuts on the E side of road S of Heath near the top of the hill. Center of e1/2 sec.35 t14n r19e.

Fossils found here

Orbiculoidea interlineata
Lingulata · Discinidae
Antiquatonia
Strophomenata · Productellidae
Buxtonia
Strophomenata · Productidae
Leiorhynchus
Rhynchonellata · Leiorhynchidae
Permophorus
Bivalvia · Kalenteridae
Angyomphalus excavatus
Gastropoda · Gosseletinidae

Records and references

Data: Paleobiology Database collection 5623 (CC BY 4.0) — view the source record

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Questions about USGS "blue file" Loc. 13366

Can you collect at USGS "blue file" Loc. 13366?

It depends on who owns the land and whether a mining claim covers it. BLM land usually allows hand collecting for personal use, national parks allow none, and private land needs the owner’s permission. Pro members see the owner and any claims at this spot.

What minerals are found at USGS "blue file" Loc. 13366?

Fossil.

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Source: Paleobiology Database.