Hosselkus Limestone, Marine limestone formation in Plumas and Shasta Counties, California.
The Hosselkus Limestone extends from Spanish Ranch to Pit River, reaching heights of 140 feet with diverse geological compositions including granite and slate.
The formation dates back to the Late Triassic period, approximately 237 to 201 million years ago, when marine environments dominated the region.
Scientists have documented 208 invertebrate species within this formation, making it a central location for paleontological research in California.
Researchers access the formation through Brock Mountain in Shasta County, where multiple outcrops provide opportunities for geological examination.
The limestone contains fossils of extinct marine creatures including ichthyosaurs like Merriamia and Nectosaurus, revealing an ancient underwater ecosystem.
Location: California
GPS coordinates: 40.06000,-120.72000
Latest update: March 3, 2025 20:59
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