The Trilobite Wilderness is a wilderness area in the Marble Mountains of the eastern

Mojave Desert The Mojave Desert (; ; ) is a desert in the rain shadow of the southern Sierra Nevada mountains and Transverse Ranges in the Southwestern United States. Named for the Indigenous peoples of the Americas, indigenous Mohave people, it is located pr ...

in northeastern

San Bernardino County, California San Bernardino County ( ), officially the County of San Bernardino and sometimes abbreviated as S.B. County, is a County (United States), county located in the Southern California, southern portion of the U.S. state of California, and is locat ...

. It is named for the large number of

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

fossils that can be found within its boundaries. Aside from its

paleontological Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

significance, it is home to typical flora and fauna of the Mojave Desert, including a stable population of

bighorn sheep The bighorn sheep (''Ovis canadensis'') is a species of Ovis, sheep native to North America. It is named for its large Horn (anatomy), horns. A pair of horns may weigh up to ; the sheep typically weigh up to . Recent genetic testing indicates th ...

and

desert tortoise The desert tortoise (''Gopherus agassizii'') is a species of tortoise in the Family (biology), family Testudinidae. The species is native to the Mojave Desert, Mojave and Sonoran Deserts of the southwestern United States and northwestern Mexico ...

. The area was created as an addition to the

National Wilderness Preservation System The National Wilderness Preservation System (NWPS) of the United States protects federal government of the United States, federally managed Wilderness, wilderness areas designated for preservation in their natural condition. Activity on formally ...

in 1994 as a part of the

California Desert Protection Act The California Desert Protection Act of 1994 is a federal law () sponsored by Senator Dianne Feinstein, passed by the United States Congress on October 8, 1994, and signed into effect by President Bill Clinton on October 31 of the same year, tha ...

. The site is managed by the

Bureau of Land Management The Bureau of Land Management (BLM) is an agency within the United States Department of the Interior responsible for administering federal lands, U.S. federal lands. Headquartered in Washington, D.C., the BLM oversees more than of land, or one ...

. It is one of six wilderness areas in

Mojave Trails National Monument Mojave Trails National Monument is a large U.S. National Monument located in the state of California between Interstate 15, Interstates 15 and Interstate 40, 40. The park was created to preserve a wide variety of geological and cultural features i ...

, established in 2016.

Geology

In the early

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

, fossiliferous

sediments Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

from a shallow sea were deposited upon a

basement A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...

Proterozoic The Proterozoic ( ) is the third of the four geologic eons of Earth's history, spanning the time interval from 2500 to 538.8 Mya, and is the longest eon of Earth's geologic time scale. It is preceded by the Archean and followed by the Phanerozo ...

granite and later

uplifted ''Uplifted'' is the second studio album by Nigerian singer Flavour N'abania. It was released on July 20, 2010, by Obaino Music and 2nite Entertainment. The album features guest appearances from Jah Dey, Oloye, Stormrex, Waga Gee, Asem, Stone, M-Ja ...

to form the Marble Mountains. These sediments – the Latham Shale Formation – are between and thick. Deeper sediments were

metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

into

quartzite Quartzite is a hard, non- foliated metamorphic rock that was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tecton ...

and form a thin layer ~ thick between the shale and basement granite.

Fossils

The abundance of trilobite fossils, some measuring as long as , give the wilderness area its name – in places virtually every piece of extracted rock contains pieces of fossil trilobite. Trilobites from the order

Olenellina Olenellina is a suborder of the order Redlichiida of trilobites that occurs about halfway during the Lower Cambrian, at the start of the stage called the Atdabanian. Olenellina are arguably the earliest trilobites in the fossil record as members ...

are predominant, but 12 species of trilobite have been discovered in this area. Full specimens are rare, with trilobite heads being the most commonly found feature, potentially indicating the area was the site of a trilobite

molting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...

ground. In all, roughly 21 species of Cambrian invertebrates have been discovered in the area, including

articulate brachiopods Rhynchonelliformea is a major subphylum and clade of brachiopods. It is roughly equivalent to the former class Articulata, which was used previously in brachiopod taxonomy up until the 1990s. These so-called articulated brachiopods have many ana ...

and

Anomalocaris ''Anomalocaris'' (from Ancient Greek , meaning "unlike", and , meaning "shrimp", with the intended meaning "unlike other shrimp") is an extinct genus of radiodont, an order of early-diverging stem-group marine arthropods. It is best known fro ...

appendages.

Oncolite Oncolites are sedimentary structures composed of oncoids, which are layered structures formed by the growth of one or more species of microorganisms, usually containing cyanobacteria. Oncolites are very similar to stromatolites, but, instead of ...

fossils are also found in significant quantities. This makes the area a bucket-list location for trilobite collectors worldwide.

References

{{Authority control IUCN Category Ib Mojave Trails National Monument Bureau of Land Management areas in California Protected areas of San Bernardino County, California Cambrian trilobites of North America Protected areas of the Mojave Desert Paleozoic paleontological sites of North America Cambrian fossil record 1994 establishments in California Protected areas established in 1994 Spoken articles