The geology of the GRF is easily recognizable by the thick stratification and its light beige-gray color contrasting with the red-brown colors of the lamina layered through it. This rocky formation is the result of the sedimentation that took place during the late Paleocene through the late Eocene in 3 different lakes located in today’s Wyoming, Utah and Colorado! These lakes originated in side basins that formed during the first uplifting of the Rocky Mountains during the Eocene. Hence most of the fish collected are from the Eocene era.
Two of the three ancient lakes are located in Wyoming, Fossil Lake [now a National Monument-Fossil Butte] and Lake Gosiute. The third and largest lake is located ¾’s in Utah and ¼ in Colorado called Lake Uinta. Lake Gosiute has a reported age range of about lower thought middle Eocene {about 58-42 million years ago}. Lake Gosiute is the area where we dig our fossil fish. As it stands, this system of lakes holds the record of longevity, since they are estimated to have lasted about 15 million years! This is truly amazing considering Lake Tanganyika in Africa, one of the oldest lakes in the world is ‘only’ 10 million years old. So this fossil area is unique, compared to the entire planet, for it‘s time frame of existence!
We generally dig for 7-10 days and then spend another few days prepping our Fossils. Each fossil has to be handled about 6-7 times before it is ready for sale or our private collection. First we must trim them for ease and mobility. This entails using a saw which is accessed right on the Quarry grounds. This is a wonderful thing to be able to trim your fossils and leave most of the unwanted matrix right where it belongs……at the Quarry. Then the fossils need to be cleaned and treated with a special compound used especially for fossils. This helps preserve them without altering them in anyway. Some of the fish fossils must be etched out of the matrix because they are partially covered. Not all fossils split ideally right in the middle to create two equal sides. Some do split perfectly and you may get a terrific positive and negative of your fossil fish. After your fish is cleaned and then coated with the compound, then you must soak them in white glue and water. This is about 20% glue to 80% water. You should let you fish soak in the watered-down glue mixture till all the air bubbles are released. This only takes on the average about 5-10 minutes. Then you must stand up your fossil to dry. Drying time depends on the climate you in, but over night should do the trick. This last procedure helps to keep the matrix from chipping and also helps with dust created by the matrix from getting into you home.
The Green River Formation, in the southwestern area of Wyoming, is considered one of the riches deposits of well preserved fossils in the world! In 1972 a part of the Green River Formation became a National Monument called “Fossil Butte“, and is now part of the American system of National Parks. It is presently illegal to dig fossils in this area. They have a wonderful museum where you can by mainly casts of fish fossils, any many real fossils are on display. They have a wonderful video to watch on the digging of the fish and also explains how to help preserve your fossils. The museum has quite and array of all types of fossils found in the GRF. Take a look at the Museum Fossil Pictures…………………
But, it’s the legal digging that we really want to talk about. There are several private quarries where you can legally dig fossils!* Some private quarries are a fee-dig and some are a share-dig. Most of the concerns on the fee-digs are the insurance involved in having inexperienced diggers on their property. People seem so readily to sue these days. Though usually there’s no fear from your average avid fossil diggers. But one must protect oneself. Below is Art McCollum in the Quarry working on some huge slabs. The one he is standing on weighed about 250 lbs. Needless to say I work on only the smaller slabs!
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Types of fish you will find in most abundance at the GRF are the Knightia and Diplomystus, the latter more commonly called a Diplo. Below is a picture of a Knightia in our personal collection and a Diplo that sold at our first show.
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Notice the long fin on the Diplo's belly and the 3 small fins on the bottom of the Knightia. This is the most distinguishing way to tell these two types of fish apart. They are sometimes very similar in size……though the diplo’s can run quite a bit larger than the Knightia on some occasions. In fact, when the diplos reach the 8” - 25” in size they are quite rare and pricey.
*More and more it seems that the government [legislators in office and lobbyist] has been trying to stop fossil digging and mineral mining all around the country. Even our Federal lands are becoming more “wetlands” and “parks” not permitting digging for minerals and fossils. I do believe in preservation of our national resources, but some localities are very questionable as to the reason for closing them down to the general population. Please help us keep this nation free and for the people. Fight unnecessary legislation to close down our Federal lands. It is what has made this nation great. The free exploration for mineral rights and fossils of our federal lands. It is a right of the people set down by our forefathers. It’s been a part of our free enterprise system from the signing of the Constitution of the USA