Paleocene Fort Union Formation exposed along the east side of Highway 16 at Buffalo, Wyoming, Johnson County, The site is 0.7 mile north of I-90. The shale has been melted by fire into a hard reddish slag. The fires were probably caused by lightening and is a common feature in the area. In some places the slag has an abundance of sequoia foliage, occasional cones, and other plant fragments. I've seen some great specimens from old quarries from the area and from this cut.. I only found a few plant fragments in the roadcut but am told the fossil bearing layer is actually about 20 feet up the slope.
The Upper Cambrian, St. Croixan Series, Eau Claire Formation is exposed in an abandoned quarry along the east side of County Road D 0.2 miles north of the junction of Highway 10 on the north edge of Strum, Trempeleau County, Wisconsin. Trilobite fragments, small brachiopods, and a few other fossils are abundant in places. The Eau Claire is the oldest fossil bearing formation in Wisconsin and this is one of the better exposures.
Mississippian Period, Osagean Series, Pierson Formation Limestone near Ridgedale, Taney County, Missouri. Three miles north of Ridgedale on Higway 65, four miles north of the Arkansas border, turn west on Highway 86. Continue west about four miles to Long Creek Road. There is a large sign there for the Cliffs at Long Creek. Exposures of cherty limestone occur along both sides of the highway. Some colorful chert can be collected as well as marine fossils but they are not overly abundant. Be on the lookout for black widow spiders as well.
Maynes Creek Formation exposed immediately east of LeGrand, along Highway 30, Tama County, Iowa. Cherty Maynes Creek Dolomite is interfingered with cherty Eagle City Member Limestone, the Eagle City has an abundance of brachiopods and a few other fossils. Beneath the Maynes Creek is about six feet of whitish oolitic limestone of the Chapin Formation. It has a wide variety of marine fossils. In the lowest part of the ditch is at least five feet of yellowish siltstone of the Prospect Hill Formation. It too has a wide variety of fossils but they are generally not as well preserved. At the top of the Prospect Hill is a burrowed zone. Unfortunately the Prospect Hill Formation has now been weathered to a soil. All the formations are lower Mississippian.
There is a small, old quarry north of Jesup Iowa, Buchanan County, which offers geode collecting. Take County Road V-62 (paved) north out of Jesup for 4 miles to County Road D-16 (paved). Go east on D-16 for about a mile to the Smith farm on the north side of the road. Stop at the house and pay a $10 per person fee to collect. Then follow the lane north past the house and to the old quarry east of the road. Exposed here is muddy limestone of the Middle Devonian Little Cedar Formation, Rapid Member. There are a few brachiopods and a zone of numerous trace fossils in the middle portion of the exposure. This has been a popular collecting site for years. Digging is required to find the geodes but the rock is soft.
The Upper Cambrian Lone Rock Formation is well exposed along the west side of Highway 26 at Reno, Minnesota. There is a great view of the Mississippi River to the east. In the colorful sandstones and siltstones a fair abundance of invertebrate fossils can be found, but most are small or fragmented. Trace fossils are abundant. Others include trilobites, inarticulate brachiopods, and an occasional graptilite. Calcite vugs are also present. Prolonged exposure has caused the greenish minerals in part of the bluff to change to reddish brown. I've had my best luck at the southern end about six feet above the ditch. The upper levels are inaccessible.
The Lower Pliocene Lower Purisima Formation is well exposed at Capitola Beach. Capitola is located east of Santa Cruz on Highway 1 along Monterey Bay. Park in town and walk to the beach along the wharf. Farther west is the New Brighton State Beach where collecing is not permitted, nor farther east at another park. Mudstone and sandstone layers contain an abundance of marine invertebrates, mostly bivalves, but vertebrate material has also been found. It is legal to collect vertebrte material here. We didn't find any. Most of the matrix is soft and many of the specimens are fragile. Don't leave them out in the rain. High tides may make the site inaccessible.
Iowa does not have a lot of Cretaceous age rocks with the exception of the Sioux City area in the western part of the state. Road cuts along High 12 south of Stone State Park in northern Sioux City and continuing north for at least 10 miles well expose three Cretaceous Formations. Included are sandy shales, sandstones, and some coal of the Woodbury Member Dakota Formation. It has some plant fossils, slenite crystals, and clayballs. It grades into the ovelying gray-brown shales of the Graneros Formation. The Graneros has pelecypods and fish scale and bone fossils but they are fragile. Entire fish fossils have been found in the Graneros in the area. It grades into chalky limestone of the ovelying Greenhorn Formation. The Greenhorn has abundant pelecypods, mostly Inoceramus. Some are quite large. They are thin shelled. Fish scales, teeth, and bones are also present.
Good exposures occur north and south of the junctions with County Road K-18. Not every cut exposes all three formations.