Fossil Hunting at the Green River Formation, Wyoming (BLM)
ALLOWED
No permit required
Key Conditions
- Common invertebrate and plant fossils (insects, plant impressions, ostracods) may be casually collected on open BLM land — up to 25 lb/day, no permit, under PRPA 2009
- CRITICAL: Knightia and all other Green River fish are vertebrate material, not invertebrate, despite frequent mislabeling — casual collecting does not cover them on BLM land under any circumstance
- The famous fee-dig quarries near Kemmerer (American Fossil, Fossil Lake Safari, and others) operate on leased BLM parcels or private ranch land under separate commercial authorization — not casual-use rules
- This area is checkerboarded — alternating public BLM and private sections from 19th-century railroad land grants — so confirm you're on public land before collecting anything
- Fossil Butte National Monument, a short drive west, prohibits all collecting of any kind under 36 CFR 2.1
Knightia Is a Fish, Not an Invertebrate
Wyoming's state fossil, the small herring-relative Knightia, gets casually mislabeled online as fair game for casual BLM collecting because it's so abundant here that it feels like a common invertebrate. It isn't — it's a fish, and fish are vertebrate animals. Under PRPA 2009, vertebrate paleontological material of any kind is excluded from casual, permit-free collecting on BLM land, full stop. The formation's plant impressions and insect fossils are casually collectable; its most famous export is not.
The Fee-Dig Quarries Are a Separate Legal Track, Not a Loophole
American Fossil Quarry, Fossil Lake Safari, Ulrich's Fossil Gallery, and similar operators near Kemmerer sell paid access to split shale and keep fish fossils — but they do this under their own leases on BLM parcels or on private ranch land, not under the public's casual-collecting rights. Walking onto open BLM ground expecting the same fish-keeping privilege the quarries advertise is the single most common misunderstanding visitors bring to this area.
Three Ways to Interact With Green River Formation Fossils
| Location/Method | Land Status | Fish Fossils? | Plant/Insect Fossils? | Cost |
|---|---|---|---|---|
| Open BLM land (casual collecting) | Public, checkerboarded with private | No — vertebrate, permit-only | Yes, 25 lb/day, no permit | Free |
| Fee-dig quarries (American Fossil, Fossil Lake Safari, etc.) | Leased BLM or private | Yes, standard species included in day fee | Yes | ~$65–$89/day, varies by operator |
| Fossil Butte National Monument | NPS federal unit | No — all collecting prohibited | No — all collecting prohibited | Free entry; observation only |
Verified against BLM policy documents and operator information, August 2026.
Fifty-two million years ago, an Eocene lake covered this stretch of southwestern Wyoming for roughly five million years of continuous sediment deposition. Two things happened at the bottom of that lake that don't happen at most fossil sites: a cold snap deflated fish swim bladders enough that carcasses sank fast, and the deep lake bottom ran anoxic, starving out the scavengers and bacteria that normally reduce a dead fish to scattered bone. The result is the Green River Formation's signature trait — fossils preserved in such fine-grained limy shale that stomach contents and fin rays survive intact, a level of detail found in vanishingly few other deposits worldwide.
The same conditions that preserve fish this well also preserve ferns, palm fronds, and insects — the material casual collectors on BLM land are actually permitted to take home. The formation doesn't distinguish between vertebrate and invertebrate material in how it was deposited; federal law does.
Green River Formation (BLM Land) at a Glance
25 lb (plants/insects only)
Casual daily limit
No
Fish fossils casually collectable?
~$65–$89/day
Fee-dig quarry cost
BLM Kemmerer FO
Managing office
307-828-4500
Office phone
Fossil Butte NM (~12 mi)
Nearest NPS unit
Finding Public Ground Near Kemmerer
Verify current BLM parcel boundaries directly with the Kemmerer Field Office before any collecting trip — checkerboard ownership changes are possible through land exchanges.
Best Times to Visit
Spring (May–Jun)
GoodMild high-desert temperatures and stable dirt-road access before summer heat sets in.
Summer (Jul–Aug)
FairPeak visitor season for the fee-dig quarries; open BLM ground is less crowded but daytime heat on exposed shale outcrops can be intense.
Fall (Sep–Oct)
GoodComfortable temperatures and the most stable road conditions of the year; quarry operators' visitor traffic thins after Labor Day.
Winter (Nov–Apr)
PoorSnow and mud make unpaved BLM access roads unreliable; most fee-dig quarries reduce hours or close seasonally. Call ahead.
Recommended Gear for Casual Collecting Here
- RequiredRock hammer and cold chisel— Standard tools for splitting the formation's thin, fissile shale along bedding planes to reveal plant and insect impressions.
- OptionalDental pick or fine awl— Useful for cleaning delicate insect wing detail without damaging the impression.
- RequiredBLM land status map or GIS app— Non-negotiable in this checkerboarded area — the difference between a public parcel and a private in-holding is not visible on the ground.
- OptionalPadded flat storage boxes— Split shale slabs are thin and prone to cracking further if tossed loose into a pack.
Permits & Licenses
| Permit | Required? | Notes |
|---|---|---|
| Casual fossil collecting (plants and insects) | No | No permit required for casual collection of common plant and insect fossils on open BLM land — up to 25 lb/day, 250 lb/year, personal use only, under PRPA 2009 and 43 CFR Part 49. |
| Vertebrate fossil collecting (fish, reptiles, birds, mammals) | Yes | Not available to recreational visitors on BLM land. Federal research permits are issued only to qualified paleontologists affiliated with a museum, university, or recognized institution. The practical route to legally collect a Green River fish fossil is a fee-dig quarry operating under its own commercial authorization, not a BLM casual-use permit. |
| Fee-dig quarry day pass | Yes | Several operators near Kemmerer (American Fossil Quarry, Fossil Lake Safari, Ulrich's Fossil Gallery) sell day-dig access on leased BLM or private ground. Rare and unusual species (stingrays, gars, birds, mammals) are typically excluded from the standard take-home fee and reserved for the operator or research institutions. |
Time & Seasonal Restrictions
- Knightia, Diplomystus, Priscacara, Mioplosus, Notogoneus, and every other Green River fish genus are vertebrate material — casual collecting on BLM land does not apply to them under any interpretation of PRPA 2009
- Common plant impressions and insect fossils may be collected casually, up to 25 lb/day and 250 lb/year, personal use only
- Fossil Butte National Monument prohibits all collecting of any fossil type — 36 CFR 2.1 — regardless of whether it would otherwise be casual-use eligible on adjacent BLM land
- Checkerboard land ownership means BLM and private sections alternate roughly mile by mile in this area; confirm current public/private status with a BLM land status map before collecting off a known public parcel
- No mechanized excavation or explosives for casual personal-use collecting — hand tools only
- Do not sell casually-collected material — PRPA's casual-use exemption is for personal, non-commercial use only
Equipment Notes
- Rock hammer and cold chisel — Green River Formation fossils are typically split from thin, fissile shale layers along natural bedding planes
- Rigid awl or dental pick — for cleaning fine plant and insect detail once a shale slab is split
- Safety glasses — splitting shale throws sharp flakes
- BLM land status map or GPS with parcel overlay — essential in this checkerboarded area to confirm you're standing on public, not private, ground
- Padded flat containers for transporting split shale slabs — plant and insect fossils are thin and fracture easily in a jostled pack
What People Find Here
- Fern and palm frond impressions — the most common plant fossils in the formation's shale layers; casually collectable
- Insect impressions (beetles, damselflies) — occur in the same fine-grained layers as the famous fish, casually collectable as invertebrate material
- Ostracods (tiny bivalved crustaceans) — abundant but small, often overlooked; casually collectable
- Knightia and other fish — abundant in the formation but vertebrate material; not legally available through casual BLM collecting, only through fee-dig quarry operations
- Rare vertebrate material (birds, bats, crocodilians, early primates) — occasionally surfaces at the commercial quarries; these are typically retained by the operator or donated to research institutions rather than sold with a standard day-dig pass
Penalties for Violations
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| Violation | Statute | Penalty |
|---|---|---|
| Casual collection of a vertebrate fossil (including any fish) on BLM land without a research permit | PRPA 2009 (16 U.S.C. § 470aaa-5); 43 CFR Part 49 | Federal felony; up to 5 years imprisonment and $20,000 fine for a first offense; up to 10 years and $100,000 for subsequent or commercial-intent violations; collected material and tools used are subject to forfeiture |
| Exceeding the 25 lb/day or 250 lb/year casual-use limit, or reselling casually-collected material | PRPA 2009; 43 CFR § 49.810 | Federal violation; up to 2 years imprisonment and $10,000 fine |
| Collecting inside Fossil Butte National Monument | 36 CFR 2.1 | Federal citation; fines and possible confiscation of tools and specimens |
| Collecting on private land within the checkerboard pattern without landowner permission | Wyoming criminal trespass statute, Wyo. Stat. § 6-3-303 | Misdemeanor trespass charge; separate from any federal fossil-resource violation |
Etiquette & Leave No Trace
- Confirm land status before you start splitting shale — the checkerboard pattern here means a productive-looking outcrop 200 yards from a public parcel can be private ground
- Leave any bone-textured or fish-shaped impression in place and photograph it rather than attempting to remove it — this is the single easiest way to accidentally commit a federal felony in this formation
- Re-stack split shale waste away from the working face rather than scattering it, so the next collector isn't picking through your discards
- If you want a fish fossil, budget for a fee-dig quarry rather than hoping to find one legally on open BLM ground — the two experiences are not interchangeable
- Respect Fossil Butte National Monument's boundary signage; the monument sits within the same broader Green River Formation outcrop and is easy to wander into from adjacent BLM land
Nearby Alternatives
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| Site | Distance | Notes |
|---|---|---|
| Fossil Butte National Monument | 12 mi | Same Green River Formation, but all collecting is prohibited under 36 CFR 2.1. Free entry and a visitor center with exhibits explaining the fish preservation the BLM land next door can't legally offer you a piece of. |
| Como Bluff (BLM, Wyoming) | 165 mi | A different formation entirely (Sundance/Morrison, not Green River), but the same casual-collecting/vertebrate-carve-out framework applies — a useful comparison for understanding PRPA's consistent logic across Wyoming BLM sites. |
Frequently Asked Questions
Can I keep a Knightia fish fossil I find on BLM land near Kemmerer?
No, not through casual collecting. Knightia is a fish — vertebrate material — and PRPA 2009 reserves all vertebrate fossil collection on BLM land for permitted researchers. This surprises a lot of visitors because Knightia is Wyoming's state fossil and is sold everywhere in Kemmerer gift shops; those specimens come from the fee-dig quarries operating under separate commercial authorization, not from casual collecting on public land.
If fish fossils aren't casually collectable, why are there commercial quarries selling them right next to BLM land?
Several operators near Kemmerer — American Fossil Quarry, Fossil Lake Safari, and others — hold their own leases on BLM parcels or operate on private ranch land, separate from the general public's casual-use rights. A day-dig fee (roughly $65–$89 depending on the operator) buys access under that specific commercial arrangement, not a BLM casual-collecting permit.
What can I actually collect for free on open BLM land here?
Plant impressions (fern fronds, leaves) and insect fossils, both classed as invertebrate/plant material under PRPA 2009 — up to 25 lb per day, no permit, personal use only. These occur in the same shale layers as the fish but require no permit because they aren't vertebrate material.
How do I know if I'm standing on BLM land or private land near Kemmerer?
This area is a legal checkerboard — alternating one-square-mile sections of BLM and private land dating to 19th-century transcontinental railroad grants. There's no visual boundary in the field. Check a current BLM land status map or GIS layer, or contact the Kemmerer Field Office at 307-828-4500, before collecting anywhere you haven't specifically confirmed is public.
Is Fossil Butte National Monument the same place as the BLM collecting land?
They sit within the same Green River Formation outcrop but are different jurisdictions. The monument, a National Park Service unit about 12 miles from Kemmerer, prohibits all collecting under 36 CFR 2.1 — even the plant and insect material that would be casually collectable on the adjacent BLM parcels.
Why are Green River fish fossils preserved so well?
The Eocene lake that deposited this formation went through a cold spell that made dead fish sink before decomposing, and the lake bottom itself was oxygen-starved, which kept scavengers from disturbing carcasses once they settled. That combination is why fish here preserve down to fin rays and stomach contents, rather than as fragmented bone scatter typical of most fossil sites.
Disclaimer
Information is provided for general guidance only. Regulations change frequently. Always verify current rules with the official jurisdiction before relying on this information for legal decisions. Permitted Pursuits is not a substitute for official agency guidance. Report an error.
Sources
- BLM — Paleontological Resources Preservation Act Casual Collecting Policy (IM 2009-113)(accessed 2026-08-03)
- BLM Kemmerer Field Office(accessed 2026-08-03)
- eCFR — 43 CFR Part 49, Paleontological Resources Preservation(accessed 2026-08-03)
- Fossil Basin — Fossil Hunting & Digging (Kemmerer-area quarry directory)(accessed 2026-08-03)
- USGS/Wikipedia — Green River Formation, Fossil Lake geologic summary(accessed 2026-08-03)
Last verified: 2026-08-03 · Last updated: 2026-08-03