Geology: Inyo County, containing many elevation extremes, has the highest summit in the continental US (Mt. Whitney), and the lowest area in the Northern Hemisphere (Badwater Basin). The canyon is especially perfect for fossil hunting because it drains the water from a large portion of the Inyo Mountains, causing the water to cut a canyon and expose layers of fossils.
Paleontology: Well preserved Paleozoic invertebrate fossils, some 485 to 415 million years old, can be found in the canyon.
Blue Green Algae is commonly found.
So are horn coral.
Works Cited (Highly Recommended to Find More Information) :
“Approach the bluffs from an access point on the southeast side of the Rio Dell/Scotia bridge. Walk along the railroad tracks (abandoned) under Highway 101 to the Bluffs. There is no automobile access beyond the parking lot that belongs to Pacific Lumber. Check in with their guard. If you’re lucky, it’s the gentleman who knows more about the local fossils than just about anyone else in Humboldt. Park your car with him or his coworkers.
Be sure to take a knapsack or backpack as this is a hike out to the bluffs. Walk along the tracks until you can see the railroad bridge. This is where the big pelecypod mollusks (look like the Shell Oil insignia) are found in mudstone or eroding out. they can be up to about 9 inches across if complete.
Cross the railroad bridge with caution to an exposure of sandstone or sand. This is the area which produces sand dollars and concretions which contain mollusks and other fossils.” (from Fossil Localities, cited below).
Geology of the Area:
The Scotia Bluffs sandstone was deposited around two million years ago during the Pleistocene epoch. The fine to medium grained sediment has a maximum thickness of 640 m. It is part of the Upper Wildcat group and overlies the Rio Dell Formation in Humboldt County. Additionally, the cliffs are about 15 miles from the coast and are at an elevation of 550 feet.
Paleontology of the Area:
Shallow fossil marine life from the Pleistocene epoch can be found in the bluffs, with many of the species still thriving today. According to “Unearthing Evidence of Creatures from Deep Time” by Leslie Scopes Anderson, Giant Pacific Scallop (Petinopecten sp.), Clam (Thrasia sp.), Cockle Shell (Clinocardium meekianum), Sand Dollar (Scutellaster sp.), Moon Snail (Nautica clause), Pandora shell (Pandora sp.), Razor Clam (Siliqua oregonensa) and Shelly sandstone (Psephidia sp.) have been recovered from the area. See image below.
The pits are composed of heavy oil fractions called gilsonite, which emerged from the Earth as oil. These deposits had become topped with water, dust, and leaves. Animals would venture in and become trapped, luring predators who come to eat the animals and become trapped themselves. The thick tar then encases the bones, preserving them remarkably well.
The preserved organisms in it are mainly from the Pleistocene epoch, although a great deal of finds date from prehistory (10 kya — 4 kya). Saber-toothed cats, mastodons, ground sloths, bison, western horse, and camelids are . Dire wolves are the most common large land mammal found there.
The La Brea Tar Pits Museum has made a beautiful timeline of the creatures found in the tar pits here.
Learn More about the Tar Pits and the Museum here, and watch Will Ferrell speak sabertooth.
According to the Mt. Diablo Interpretative Association, Mt. Diablo is a mountain with an elevation of 3849 feet in the Diablo range. Although the mountain has only very recently emerged, the rocks it is composed of are very old. Due to its complex geological history, the rocks of Mt. Diablo can be divided into three groups, Mt. Diablo Ophiolite (Jurassic), Franciscan Complex (Jurassic and Cretaceous), and Great Valley Group (Jurassic and Cretaceous). Additionally, the younger sedimentary rocks on the higher strata are Cenozoic.
Mt. Diablo Ophiolite: An ophiolite is a part of oceanic crust and the underlying upper mantle that has been uplifted and exposed above sea level and often developed onto continental crustal rocks. According to radioactive and fossil-age determinations, the ophiolite emerged approximately 165 million years ago. The ophiolite basalt has a crystalline feel with a black to greenish-brown hue. This is created when lava erupts underwater and ‘freezes’ when it makes contact with the water. Diabase is a coarser version of the ophiolite basalt that is created by lava erupting from vertical fissures underwater. Serpentinite can also be found on Mt. Diablo.
The middle area of the Mt. Diablo strata known as the Franciscan Complex is the result of 140 million years of east-dipping subduction. Concerning fossils, approximately 10% of the Franciscan Complex is composed of shale. Unfortunately, most of it has been converted to argillite as a result of metamorphism.
The Great Valley is composed of sedimentary shale and sandstone from the Upper Jurassic to the Cretaceous period. It is mostly deep-water shale. There are also younger Cenozoic strata on top. As a result of the drying of Central Californian basins during the Miocene and Pliocene, marine fossils end at that time.
Paleontology and Fossils:
Cow and Aelurodon jaws have been found, in addition to plants. Marine fossils from both deep and shallow water environments have been recovered.
Directions to Finding Fossils at Mt. Diablo:
Driving Directions: “In Walnut Creek on Interstate 680, take Ygnacio Valley Road east to Oak Grove Road. Turn right (south) and continue as this road becomes Castle Rock Road. Proceed to the end of the road where it is blocked by a gate and there is parking on the left. Access is free.” (Geohiking.com)
Once you arrive:
“From the parking area, you will notice the equestrian and cyclist trailhead across the road. The hikers’ route is past the gate on the paved road into Castle Rock Park. You can take either. Walk up the paved road into the park past the picnic area, swimming pool, and park buildings. This is a private park, but hikers are allowed trail access through it. The road turns to gravel past the restrooms. You will be walking through Pine Canyon alongside Pine Creek all the way with moderate shade. The trail is an old wagon road called Stage Road (and signed that way as well).
Leaving Castle Rock Park behind, you will pass a gate and continue to a fork. Bear right to stay on Stage Road. Before long you arrive at a sandstone wall on the right.
A short distance further you arrive at a rock on the right with a hole bored through it by water erosion. You won’t be the first person to climb up into the round room inside the rock.
There are many creek crossings on this trail, seven of them, and it may not be much fun from December to March, depending on rainfall and horse traffic.
After the first stream crossing, you will spot a narrow footpath leading to the right through the grass. In spring when the grass is growing, this path may not be apparent. If you come to the second creek crossing, you missed it, but by turning right and following the edge of the creek a short distance, you will be there. Take the footpath past a grape arbor of sorts to a slide in a tall cliff above the creekbed. There is a rich layer of marine fossils in this cliff. Some of these wash down to the creekbed each year. If you look carefully for whitish rocks, you will find pieces of this exposure. Thick clusterings of mollusk shell fragments can be seen. This sort of rock, composed mainly of shells with some sandstone is known as a “hash” for somewhat obvious reasons. Shell hashes in the Diablo foothills are generally of the Briones Formation. You can see these on Rocky Ridge in Las Trampas Regional Park, Fossil Ridge on Mt. Diablo, and various other locations in the area. If you look closely at the shell pieces, you may find some that are large enough to recognize as a clam, the dominant type of fossil. Pectens, the bivalve mollusk made famous as the symbol for Shell Oil Company, also occur, but are less common.” (Geohiking.com)
Disclaimer: California Fossils focuses on hosting a user-friendly interface and a flexible platform where your finds can be published almost instantly. However, we realize that increased traffic to fossil sites leads to erosion and degradation of sites, which is why we strongly recommend not removing fossils and leaving them where they have been found for others.
The Sespe Wilderness lies within the Transverse Mountain Ranges. The USGS has information on the geological setting of the mountain range province here. More specifically, the Sespe Wilderness and Sespe Condor Sanctuary are mostly within the Topatopa Mountains and foothills. The Topatopa Range is composed of Oligocene-Eocene age sandstones of the Juncal, Matilija, Cozy Dell, and Coldwater Formations. The uplifting of the Topatopa Mountains was chiefly caused by the San Cayetano fault, which was initiated at 1.9 Ma.
The fossils in the Sespe Wilderness are incredibly common and can be found on the trail and in the abundant boulders nearby. Marine shells can be seen exposed on the outside of eroded and smooth boulders, and on the surface of the rotated strata of the foothills.
A variety of marine invertebrates are common in the area, including mussels, oysters, cephalopods, and other shelled organisms.
The cliffside of this beach contains shale from the Monterey Formation. The fossiliferous shale dates back to the Miocene epoch. There are talus slopes in many areas created by folded and slanted strata.
Be careful of falling shale from the cliffside. Although it poses a hazard, the fallen rocks are more convenient to split than extracting shale from the outcropping. Split fishes can be found near the bottoms of the formation. Additionally, petrified whale bone has been recovered on the beach.
As you can see in the figure above, three prominent outcroppings jut out from the Monterey formation, marked 1, 2, and 3 on figures B and C above. Figure A shows that Jalama Beach, to the left of Gaviota, is part of the Monterey Formation bearing marine Miocene fauna, and Oligocene rocks are found more inland.
Fossil fish and petrified whale bone are in the outcroppings.
The Sperry Wash in the Alexander Hills near Death Valley contain sediments from the surrounding China Ranch beds. The China Ranch beds are over 5000 feet thick and contain conglomerate Pleistocene lake deposits. The upper beds contain marly limestone and tuffs.
Although before 1966 the area was considered unfossiliferous in exception to the wood fragments found in the stretch of road described below, permineralized tree ferns, palm axes, rootlets, and material referred to as petrified bog have been found in the area. Additionally, permineralized grass species such as Tomlinsonia are fossilized in the sediments.
According to Gail Butler’s Rockhounding California, From the interstate 127, turn east on Furnace Creek Road. After driving for 4 miles southeast, stay on Furnace Creek when it branches right away from Old Spanish Trail Road. Turn right on Western Talc Mine Road and drive 2.5 miles to the talc mine. Fossil algae and talc can be found by the mine. Then back out and continue driving for another 4.7 miles farther. Agate and petrified wood can be found on both sides of the road in that stretch of road.
Tidwell, William D. and Nambudiri, E. M. V., “Tomlinsonia stichkania sp. nov., a permineralized grass from the Pliocene to (?)Pleistocene China Ranch beds in Sperry Wash, California” (1990). All Faculty Publications. Paper 1446. http://scholarsarchive.byu.edu/facpub/1446
Gail Butler, “Rockhounding California,” (Morris Book Publishing, 1995)
The yellow brown sandstones that contain the fossils are part of the Purisma formation. Collecting is best at low tide, when the outcroppings are most exposed.
Paleontology of the Fossils:
The fossils originate from the Pliocene epoch of the Neogene period. Bivalves, gastropods, sea urchins, crabs, marine mammal bones from whales and seals can be found. Shark teeth have also been recovered from the beach, but are rare.
Fauna found in the area include three species of Echinodermata, two Cirripedia, Pelecy- poda, and 29 Gastropoda. Many new gastropod species were discovered in Jacalitos Creek including Attralium arnoldi, Chrysodomus coalingemis, Fissuridea subelliplica, Murex perangulatui, Natica (Neverita) orbieularis, Trophon magister, Turritella nova; Pelecypoda : Mytilus ketvi, Tivela trigonalis.
The mountains contain a rich outcropping of the Latham shale, known for its diversity of lower Cambrian fossils. The fossils are approximately 518 million years old. The Latham shale borders the Cadiz and Chambless Formations, both named after the small towns nearby. However, the land has become part of a nationally preserved area, so the BLM recommends only one trilobite per person.
The most common fossils in the shale are trilobites of the Olenellina genus, which are distinguished by their lack of facial structures, and the cephalon or head molted as a single piece. However, brachiopods including some of the earliest articulate brachiopods (meaning they have hinge teeth) have been found in the Latham shale. Hyoliths, trace fossils, and very rarely an Anomalocaris specimen are in the shale at the Marble Mountains.
According to the Bureau of Land Management, “This area can be found by taking historic route 66 to the town site of Chambless then taking Cadiz Road approximately 4 miles south. At this point the road turns sharply to the left (east) You will see Cadiz Farms housing on the left side of the road. Continue on east for two miles and just before reaching the rail road crossing turn north on Route (Rt.) NS376 for .4 miles at the intersection with Rt. NS299 drive east for .2 miles. your final turn will be north on NS380 for .7 miles park here near the base of the mountain and hike west to east along the wash. Hiking up the mountain and looking down hill will allow you to see where others have excavated pits in the shale and help indicate where fossils have been found.”