Fossil Point is a prominent landmark in Lake Clark National Park and Preserve on the southern shore of Tuxedni Bay, at the north end of Tuxedni Channel and west of Chisik Island, about 56 miles (90 km) southwest of Kenai and 54 miles (87 km) northwest of Homer, Alaska. The name “Fossil Point” first appeared in 1912, published by the US Coast and Geodetic Survey. Lake Clark National Park and Preserve was initially designated a national monument by President Jimmy Carter on December 1, 1978, under the Antiquities Act. It was established as a national park and preserve in 1980 through the Alaska National Interest Lands Conservation Act. The park spans from Cook Inlet in the east across the Chigmit and Neacola Mountains to the Mulchatna River watershed in the west. It safeguards the Cook Inlet coastline, alpine tundra, glaciers, glacial lakes, major salmon-bearing rivers, and the volcanoes Mount Redoubt and Mount Iliamna, both over 10,000 feet (3,050 m), which vent steam from their snow-capped craters. Tuxedni Bay is about 4 miles (7 km) wide at its mouth and narrows as it extends inland 12 miles (20 km) to the braided delta of the Tuxedni River. Chisik and Duck islands lie at the mouth of Tuxedni Bay. The geology of the bay was first described by Karl Eduard von Eichwald, based on samples collected in 1871 by Russian mining engineer Peter P. Doroschin and sent to Saint Petersburg. Eichwald, of German ancestry, was from present-day Latvia but spent much of his career in Saint Petersburg as a leading geologist. The Tuxedni Bay region contains approximately 26,600 feet (8,100 m) of Early, Middle, and Late Jurassic rocks, formed around 201 to 145 million years ago. This may be one of the thickest and most complete sequences of bedded Jurassic rocks in the United States. The rocks at Fossil Point are part of the Tuxedni Group, layers of marine sedimentary rock 4,970 to 9,715 feet (1,515-3,000 m) thick, deposited in a deep ocean trench during the Middle and Late Jurassic. They now consist of graywacke sandstone, conglomerate, siltstone, and shale, with prolific fossil invertebrate marine fauna.

The glacial history of the Tuxedni Bay area is not well known due to a lack of glacial deposits. Late Pleistocene and Holocene glacial moraines have been mapped near the current terminus of Tuxedni Glacier. A small remnant moraine, attributed to the Naptowne Glaciation, is located on the north shore of the bay, and some Naptowne-age deposits are mapped in drainages entering Tuxedni Bay from the south. However, recent alluvial and colluvial deposits obscure most evidence of past glaciation. The end of the most recent stage of the Naptowne Glaciation is dated to about 11,000 years ago in other parts of the Cook Inlet basin. The presence of glacial ice may have restricted prehistoric human passage through upper Tuxedni Bay. Sockeye and chum salmon are present in the Tuxedni River at the head of Tuxedni Bay, and a significant run of sockeye enters Crescent River, heading for Crescent Lake. Pacific razor clams are abundant on sandy Cook Inlet beaches. These resources have attracted human settlement since the area was deglaciated. Magnetic Island, a small island on the north side of Tuxedni Bay, is surrounded by mudflats submerged during high tides. The island, named for compass deviations observed during a geological survey in 1951—likely due to magnetite—offers crucial evidence of prehistoric human habitation from approximately 4,100 to 3,500 years ago. Excavations in 2012 revealed a series of depressions containing fire-cracked stones, hearths, and stone tools linked to the Arctic small tool tradition. Around 3,500 years ago, volcanic activity increased in the Chigmit Mountains and along the Alaska Peninsula, possibly burying the Magnetic Island site in ash and halting the spread of Arctic Small Tool tradition people into the Cook Inlet basin. Following the Alaska Purchase in 1867, Tuxedni Bay attracted miners and fishers. A clam cannery operated at Snug Harbor on Chisik Island from 1919 to 1980, and commercial and subsistence salmon fisheries continue today. The bay’s shores now feature multiple private and Alaska Native inholdings.

Fossil Point is significant for hosting one of Alaska’s most productive marine invertebrate fossil sites. Known to Cook Inlet fishers, it is protected against collecting, yet private collectors often display specimens in local homes and businesses. The most common megafossils here are Middle Jurrasic bivalve from the genera Retroceramus, Pleuromya, Pholadomya, and Pinna, and the cephalopods Belemnites and Ammonites. Eichwald identified four new species of the genus Inoceramidae, now called Retroceramus. However, contemporary paleontologists debate whether these are distinct species or ecological variants of one or two species. Pleuromya was a burrowing bivalve in soft sediment, with only its long siphon tubes reaching the sediment-water interface. Its fossils are often found in a life position with the posterior end directed upward. Pholadomya is a genus of saltwater clams, with one species remaining in the Caribbean. Pinna, commonly known as pen shells, is a genus of bivalve mollusks that can grow to a length of about 31 to 35 inches (80–90 cm). These bivalves are widely distributed and are characterized by thin, elongated, wedge-shaped, and nearly triangular shells with long, toothless edges. Typically, they lie point-first on the sea bottom, anchored by a net of byssus threads. Belemnites belong to an extinct group of cephalopods that were fast-moving, nektonic carnivores during the Early Jurassic period. Ammonites, also extinct cephalopods, are related to living octopuses, squid, and cuttlefish, although they more closely resemble the nautilus. The last species of ammonites disappeared either in the Cretaceous–Paleogene extinction event or shortly thereafter, during the Paleocene. Read more here and here. Explore more of Fossil Point and Tuxedni Bay here: