The view from Charlie Nunn's fish fossil quarry north of Kemmerer

Green River Fossil Adventures

Digging in the Kemmerer Wyoming area fossil fish quarries is a great way to spend a few days in the heat of the summer. The quarries are productive, and you have several choices to pick from, depending on how comfortable you are with your skills lol. This page is partly a chronicle of my adventures in the area but also a guide to the best digging areas and techniques that will get you the most fish for your time and $$.

The Fossils

From the National Park Service comes this bit of scientific wisdom:

This 50-million year old lake bed is one of the richest fossil localities in the world. Recorded in limestone are dynamic and complete paleoecosystems that spanned two million years. Preservation is so complete that it allows for detailed study of climate change and its effects on biological communities.

Well, it ain't limestone. So much for the government geniuses. Here's the real scoop from Fossil Museum:

Class actinopterygii, the ray-finned bony fishes, comprise almost half of all known species of vertebrates, some 20,000 extant species. There are numerous locations worldwide that are noted for wondrous preservation of bony fishes, and the Green River formation that covers some 25,000 square miles of SW Wyoming, west Colorado and east Utah is one of them. The formation is one of the largest lacustrine (i.e., lake) sedimentary accumulations in the world, averages some 2,000 feet thick, and spans the period 40 to 50 million years ago during the Eocene Epoch of the Cenozoic Era.

The Green River Formation is actually a heterogeneous complex of lakes differential in ecological, geological characteristics, timeframe and hence fauna and flora. The complex comprises three primary lakes formed as a consequence of drainage from tectonic highlands envolved in the uplift of the Rocky Mountains during Tertiary time. Fossil lake, centered in Southwest Wyoming, is the smallest and appeared briefly during the early Eocene. The Lake Gosiute deposits span the period from Lower to Middle Eocene, and the largest deposit from Lake Uinta that ranges across the Utah-Colorado border, spans most of the Eocene Epoch.

During the Eocene, based on the fossil record, the region was sub-tropical to temperate. Some 60 vertebrate taxa have been described from the formation, as well as abundant invertebrates and plants. Green river has been noted for its well-preserved fish since mid-way through the 19th century. The unusually excellent preservation of the Green River fish fossils is usually attributed to a combination of two factors: 1) a cold period during the Eocene that would have caused dead fish to sink faster due to a less inflated swim bladder; and 2) the great depth of the lakes and the consequent anoxic conditions that would have often prevented scavengers from disturbing the carcasses.

The majority of fish fossils are taken from the Fossil L area from two layers: 1) the so-called 18-inch layer; and 2) the spilt fish layer (aka the F1 layer). The best preserved fish come from the 18-inch layer. Because the sediment is highly laminated, the fish can often be removed nearly whole. This layer, in the area near Fossil Butte, does indeed average about 18 inches in thickness, and represents some 4,000 (years) of deposition. The composition of the limestone (actually oil shale - where do they keep getting limestone from?) indicates that the layer was formed in deep water far from shore. By contrast, the so-called split-fish layer is unlaminated making extraction and preparation of the best fossil fish far more difficult. The layer is about six feet thick, and the fauna indicates water that was better circulated than that associated with the 18-inch layer. Some 19 genera of Eocene fish come from the Green River formation.

Here is a diagram of the stratigraphy of Fossil Lake, the unit that the Kemmerer quarries are located in. The "sandwich beds" are better known as the split-fish layers.

Of course the coolest thing about the Green River formation is the fossils themselves. I suggest you start your visit at the Fossil Butte National Monument on Highway 30 west of town; they have a tour and great fossils and information in the visitor's center. June-August, Visitor Center Hours 8:00a-7:00p; Winter Visitor Center Hours 8-4:30 (September through May). Closed winter Holidays.

Here are some fish from my and other collections; you won't find many of these but the Knightia and Diplomystus are extremely common in the quarries, while Prisacacara, Phareodus, and Mioplosus are fairly common. Stingrays, gars, bowfins, etc. are so rare you will probably only see parts lol. The Diplomystus dentatus, was a large predator, up to 26", but most you will find are juveniles, common up to 6" or so.

>A Diplomystus dentatus from the share dig quarry (Charlie Nunn's) north of town

This adult Diplo is mine from the 18-inch layer and is about 14" long.

This is Knightia alta, relatively common in the quarries. It's a small herring that swam about the deeper parts of the lakes eating plankton in huge schools. Every other fish ate them lol. This one is from Warfield's old quarry in the F1 layer south of town.

This is Knightia eoceana , extremely common in the quarries. In fact, 95+% of the fish you dig will be these. It's a herring too and every other fish except Knightia alta ate them :) This one is from Warfield's old quarry too.

This is the head of a large perch, Priscacara liops ("Prisky" to the diggers - it's easier to pronounce :). They grew up to 15" long and ate snails, crustaceans, fish, and probably just about anything else. This is a good example of why you need to keep track of where you are in the layers; the diggers who found this will recover the rest of the fish as they get deeper into the rock. From Charlie Nunn's quarry.

This is a juvenile Priscacara serrata from the 18-inch layer.

This is my Priscacara hypsacantha from Nunn's quarry. They preyed on ostracods (aka fairy shrimp). They are relatively common in the quarries.

This is a sucker, Notogoneus osculus, closely related to living suckers. They must be pretty rare because I have never heard of one from the split-fish layer.

Mioplosus labracoides, a predator that grew up to 20" long. Yikes! From the 18-inch layer, and I wish it was mine but it's not!


And this is the fearsome Phareodus testis, the coolest fish in the quarries (IMHO). They are related to the Amazonian arrowana and they ate FISH! I have a 14" one that I found at Warfield's old quarry south of town. You will find many exploded fish in the quarries (aka "Explodeodus"!) but very few whole ones. If you do find a whole one be prepared to pay a couple hundred dollars for it.

Lepiosteus atrox, an extinct gar. These are the prize fish of the quarries and grew up to 66" long! There are a few beautiful gar at all the galleries in town and at the monument. They ate anything that moved. If you find one don't expect to keep it unless you are willing to pay big money for it. As in thousands of dollars. Many thousands :(


A juvenile Heliobatus, a freshwater stingray, from Nunn's quarry. I doubt you could buy the adults for less than $500 if you are share or fee digging. Rays are a prize fish at the quarries and practically all the fee dig places take them. I think that $750-$1000 is a fair deal if you dig one yourself and want to buy it. They are usually $2,500 - $5,000 retail.

Bits & pieces of a Heliobatus stingray. They probably didn't find all of this one, which is a shame because it's a killer fossil!

Fee Digging

After the National monument, visit Ulrich's Fossil Gallery (the quarry is visible east on 30 a few miles, on the right) to see their fossils. You can dig there but you don't get much for your money and it's highly supervised. In other words you dig the small, cheap fish and they dig the big, nice ones. The dig starts at 9 a.m., every day Memorial Day to Labor Day. You are allowed to recover 6 - 8 complete fish which you can easily do in the time allotted, for $55. A $65 fee allows you to collect all common specimens except those designated as rare and unusual by the State of Wyoming to include stingrays, gars, birds, all mammals, etc. You would be allowed any and all sizes of Mioplosus, Phareodus, Priscacara, Knightia, Diplomystus, Notogoneus. Pay the extra $10 just in case. If you go cheap and find a nice fish you will want to shoot yourself, trust me. While Ulrich's is not exactly my cup of tea, if all you want is a few fish without paying $20 each, this one is for you.

Warfield's Fossils has a fee dig quarry north of town. They used to have a great F1 quarry south of town at Warfield Springs; some pics of the quarry are below. It was a great place to camp out & get away from it all. Unfortunately they closed that quarry to fee digging for reasons unknown to me and opened one right next to the share dig quarry that I dig at. They are open from Memorial Day weekend until August 31st. Hours are from 8am to 4pm 7 days a week. Reservations are NOT needed for groups UNDER 10 persons. It is $75.00 per day per digger for 1 to 9 people. It is $60.00 per day per digger For 10 or more people. It is $60.00 per ½ day per person (4 hour dig at any start time) or $25.00 per hour. Children 12 and under may collect fossils in the tailings pile at ½ price. They keep everything that you would expect them to keep. You can have all Knightia, Diplomystus, Mioplosus, Priscacara, Phareodus, and Amphilplaga. Not that I have ever seen one of the latter.

If you ever needed to cool down the springs are right there & the water was cold & great tasting!

The main quarry at the springs. There was an 18-inch layer quarry there too.

One of our first fish from Warfield's :)

The old Pooper at the quarry. The tarp is covering a crocodile that they were working on!

If you don't like to pay to dig (I know I don't, not when I am digging for 4 or 5 days), you can try share digging. The only quarry that I know of that you can share dig at is Charlie Nunn's quarry which is just to the west of the new Warfield's quarry north of town. Follow their map but stay left at the Warfield's quarry sign; Charlie's quarry is 100 yards down the hill. I know that Antares Fossils did share digging in Charlie Nunn's quarry in the past. Some other great people whom I have share dug for are Bob & Bonnie Finney (below), Jerry Hodges, and Charlie Nunn (307 877-3641). Typically, share digging involves digging in a "section" of the quarry, which is usually 50 feet of the wall. You dig the way the owners tell you to, and split the fish when you are satisfied with what you have. As usual, rare fish must be paid for, or given to the owners. If you can work out a better deal, then go for it :)

Turn by turn directions to the share dig quarry from Kemmerer:

  1. Starting at mile 0 at the junction of routes 30 and 189 in Kemmerer, drive north on 189
  2. Mile 0.3 N end of bridge over the Hams Fork
  3. Mile 0.4 Sinclair gas station on R
  4. Mile 0.5 Left onto WY 223 at "Lake Viva Naughton" sign
  5. Mile 4.7 Left on dirt road after sharp left curve; easy to miss !
  6. Mile 6.7 Dirt track to left; stay right
  7. Mile 7.2 Dirt track to right; stay left
  8. Mile 9.8 Gravesite on left
  9. Mile 9.95 Stay left at dirt track to right
  10. Mile 10 Turn left at Y
  11. Mile 11.9 Warfield's quarry to right; Charlie's quarry is straight ahead

Bob (left) and Bonnie Finney, and a friend, at the Tucson show, with a Crossophilus magnicaudatus paddlefish they found

Digging tips to get the most for your time and $$

  1. Work the wall in a systematic fashion, starting with the rock closest to the bottom and closest to you, working down to the floor, then starting on the top of the next column of rock in the wall. Work from left to right, or vice versa. KEEP A CLEAN FLOOR! That way you will never lose a piece of a big fish that you are trying to reassemble. The floor is usually marked by a layer of thin, dark brown muddy shale that can't be split to expose the fish.
  2. Split your rocks as they come from the quarry wall, as pictured below (my area in the Nunn's quarry one summer). See how the slabs are standing up against one another? That's so I can find where a partial fish came from in the slab and in the matching slab in the wall. Big fish almost never come out whole on one slab; the stone is too fractured to contain fish more than 10 or so inches long in one piece in this quarry.
  3. Look at the edge of each rock as it comes out of the wall for "sections" of fish. You will see thin dark brown lines where a fish is exposed in the fracture between blocks. Split the rock on one side of the fish, since these are "split-fish" layer quarries, it will almost always want to split on one side or another of the fish. Don't force it to split where it doesn't want to. This is a cardinal sin of digging Green River fish. You will break many fish this way.
  4. Learn to recognize sections of large fish like Priscacara and Phareodus. These often split on the backbone and each looks distinct in cross section from the common Knightia and Diplomystus.
  5. Never ever throw a partial fish away. Look for the rest of the fish in the wall. Sometimes I mark my fish with a carpenters' pencil and mark the corresponding section of the quarry wall. I start with the letter A and go up from there. The last time I spent 4 days at the Nunn quarry I was up to ZZZ or something like that lol. I didn't find all the corresponding parts of these partial fish but I found a great many of them. These can be reassembled with Elmer's glue either at the quarry or later.
  6. NEVER throw large plates away. Break them in half and look for cross sections. You will find fish this way, but this is how most of the extremely rare specimens like bats and birds are found. If you go to Nunn's quarry, ask Walt how big the plate he found his bat in was when he broke it. I was told it was about the size of his palm.

Tools you don't want to be without

  1. Square shovel. Coal shovels work good too. Round or pointed shovels are useless here; leave them at home.
  2. Estwing rock pick with the flat or chisel end, not the pointed end. Those are useless here too. Sharpen it to a RAZOR edge. This is your primary tool for splitting large slabs.
  3. RAZOR sharp spring steel wedges. These are your primary tool for splitting thinner slabs. Leave the rock chisel set at home. They are ALL too thick for splitting the shale.
  4. Multi-purpose painting tool. I got one at Wall Mart for $3.63 lol. These are GREAT for splitting slabs that don't want to cooperate with your wedges. Sharpen them to a RAZOR edge too. Buy 2 so if you ruin one you have a backup. I left my spare with Cory Hodges (Jerry's son and an expert fossil hunter) this summer; he was looking at it with envy :))
  5. LEATHER GLOVES. No cotton, wool, etc. With all those razor sharp tools you will be thankful for those gloves. I still get cuts all over my legs and arms because I refuse to wear jeans or a flannel shirt.
  6. A big rock pick such as the Estwing for clearing debris off the top and misc. chores. A bar is optional for moving those brute blocks.
  7. A carpenter's pencil to mark your sections in the wall and to mark pieces of whole fish for assembly at home.
  8. Elmer's glue to reassemble those partial fish you saved for transport home. Also newspapers and cardboard boxes are essential. Tape is optional; a layer or two of newspaper between upright slabs will protect most slabs if you don't drive like an idiot. NEVER PACK SLABS LYING DOWN! They are guaranteed to break. Stand them up in cardboard boxes and stuff the box full so they don't rub and bounce around all the way home.
  9. If you are really squeezed for space, get a battery powered circular saw with a masonry blade and saw your fish out in the quarry. Most of the professional diggers have table saws and generators to do this. Maybe the people you share dig for will let you use their saw.

Fossil Preparation Tips

  1. Use a Dremel engraver. This is your #1 tool. Set it on high and flake away the shale to expose your fish.
  2. Glue partials back together with Elmer's. You can hide the cracks by sprinkling the wet glue with powdered shale, which you will have around in large quantities after sawing some plates up :)
  3. Saw your finished plates into square shapes with a table saw and a masonry blade. This stuff is so soft you can saw a 2" thick slab like it was cold butter :) Look for cross sections of fish in those cuts! I have found some BIG fish this way that needed only a little touch-up where the saw mark was. USE A DUST MASK!
  4. Coat the finished fossils with clear nail polished mixed 1:10 with acetone. Do not use nail polish remover! It is not the same as acetone and will leave your fish with a cloudy coating that looks terrible. This will keep them from flaking and is easily removed by soaking the fossil in acetone.

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Tim Fisher

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