Rockhounding.org

Otter Fm. Fauna, Otter Fm.

Cascade County, Montana
Directions
Next site in MontanaYurek Ranch, Giffen · 9 mi

Can I collect here?

Pro
See who owns this land and whether it is claimedPro shows the owner, the claim on this spot and every claim within a mile.
Read the collecting rules by land type

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.

Nearby sites

All of Montana
9 miYurek Ranch, GiffenFossil19 miTiger Butte MammothFossil21 miVaughnSilicified Wood

More fossil sites in Montana

See them all

More sites in Montana

View all Montana sites
The Market

New on the Market

Native American arrowheadNative American arrowhead$20cubedmoons3Browse the Market

Found something here? List it for sale

About Otter Fm. Fauna, Otter Fm.

Otter Fm. Fauna, Otter Fm. is a fossil collection site in Cascade, Montana, cataloged in the Paleobiology Database. Fossils here come from the Otter Formation, dated to the Chesterian (335.4–323.4 million years ago). The depositional environment is recorded as offshore. Documented finds include Algae, Ammodiscus, Millerella, Dictyoclostus, Pugnoides, Spirifer.

Geologic setting

Formation
Otter
Geologic interval
Chesterian
Age
335.4–323.4 Ma
Depositional environment
offshore
Recorded occurrences
14
Geology notes

"red-brn shale; calcareous; calcareouos streaks and limestone nodules are fossiliferous. Intt. w/fine grain light grey ls.). Shallow, marginal marine conditions may have been more normal marine during deposition of this bed. BA2"

Locality notes

"Cascade Co., MT (#14227); coordinates based on approximated location of Cascade County, MT. Information not available for more precise assignment."

Fossils found here

Algae
Algae
Ammodiscus
NO_CLASS_SPECIFIED · Ammodiscidae
Millerella
NO_CLASS_SPECIFIED · Eostaffellidae
Dictyoclostus
Strophomenata · Productidae
Pugnoides
Rhynchonellata · Petasmariidae
Spirifer
Rhynchonellata · Spiriferidae
Nucleospira
Rhynchonellata · Nucleospiridae
Nuculana
Bivalvia · Nuculanidae
Limipecten
Bivalvia · Limipectinidae
Allorisma
Bivalvia · Edmondiidae
Bellerophontoidea
Gastropoda
Tylonautilus
Cephalopoda · Tainoceratidae
Ostracoda
Ostracoda
Conodonta
Conodonta

Records and references

Data: Paleobiology Database collection 581 (CC BY 4.0) — view the source record

Getting there

No directions yet.

How hard is it?

Getting there
– / 5
Finding anything
– / 5
Votes
0

Trip reports

No trip reports yet.

Questions about Otter Fm. Fauna, Otter Fm.

Can you collect at Otter Fm. Fauna, Otter Fm.?

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 Otter Fm. Fauna, Otter Fm.?

Fossil.

Comments

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

No comments yet.

What to bring

The whole kit
  • Estwing E3-22P Rock PickThe industry-standard 22oz geological hammer. One-piece forged steel with shock-reduction grip.See it on AmazonCompare picks
  • Clear Anti-Fog Safety Glasses (4 Pack)Adjustable, anti-fog lenses for clear vision in any conditions.See it on AmazonCompare picks
  • Watertight Medical KitCompact, waterproof first aid kit with bandages, moleskin, and field essentials.See it on AmazonCompare picks
  • Northwest Treasure Hunter's Gem and Mineral GuideWhether you're digging for the first time or are an experienced rockhound or "prospector," with a simple rock hammer and...See it on Amazon

As an Amazon Associate we earn from qualifying purchases.

Source: Paleobiology Database.