Focused condition assessment of paleontological resources within Lake Clark National Park and Preserve (revised with cost estimate)

Ruga, Mikaela; Lanik, Amanda; Hults, Chad

Lake Clark National Park and Preserve protects a variety of paleontological resources, ranging from 200 million-year-old marine invertebrates to 25 million-year-old plants. Paleontological resources, or fossils, are any evidence of life that has been preserved in the geologic record. Fossils are non-renewable resources that document the history of life on Earth; once a fossil is destroyed, that piece of Earth’s history is lost forever. Potential threats to fossils can be natural, such as erosion, or anthropogenic, such as unauthorized illegal collection (it is illegal to collect fossils from NPS lands without a permit). The purpose of this report is to provide baseline documentation of paleontological resources, including the types of fossils in the park, fossil locations, the significance of those fossils, the potential for new fossil finds, and a discussion of paleontological resource management. Each fossil locality known in the park has been rated for its level of management concern based on several parameters. In addition to this report, the NPS Alaska-wide paleontology database has been expanded to include fossils from Lake Clark National Park and Preserve. The database incorporates basic information about fossil sites with management-focused fields that can be easily queried and viewed spatially. Fossil location information is sensitive data—to access the database or for more information, contact the Alaska Region Natural Resources team. Most of the fossiliferous bedrock in the park is associated with an ancient chain of volcanic islands called the Talkeetna arc. The Talkeetna arc began erupting about 200 million years ago in the proto-Pacific Ocean, far to the south of its current position in south-central Alaska. Subsequent tectonic movements transported the Talkeetna arc from the middle of the ocean to the edge of North America. Rocks in the park include the older (mainly Triassic) oceanic crust the Talkeetna arc was built upon (e.g. Kamishak Formation, Chilikadrotna Greenstone, Kakhonak/Tlikakila Complex), the igneous rocks that form the arc itself (e.g. Talkeetna Formation), and sedimentary rocks shed off the arc as it eroded (e.g. Tuxedni Group, Chinitna Formation, Naknek Formation, Koksetna River Sequence). Fossils in the park primarily the remains of creatures the lived on and around the Talkeetna arc. The oldest fossils discovered in the park include Late Triassic (228–209 million years ago) marine invertebrates from the Kakhonak and Tlikakila Complexes. These marine invertebrates include bivalves, brachiopods, conodonts, corals, echinoderms, and gastropods. The next fossils found in the park chronologically are fern and tree stump fossils from the Early Jurassic (Sinemurian, 199–191 million years ago) Talkeetna Formation. A series of Middle Jurassic to Late Jurassic (170–152 million years ago) marine sedimentary rocks (i.e. Tuxedni Group, Chinitna Formation, Naknek Formation) overlie the Talkeetna Formation; most of these rocks contain abundant fossils, which primarily include marine invertebrates such as ammonites, bivalves, and belemnites. Finally, the youngest fossils in the park are plant fossils from the West Foreland Formation (deposited between 59 and 48 million years ago), and the Kenai Group (deposited between 28 and 23 million years ago). In addition, several rock units have produced fossils outside park boundaries, but fossils have not yet been found in these rocks in the park. These include the Kamishak Formation, Chilikadrotna Greenstone, Koksetna Rive Sequence, Kuskokwim Group and the Kaguyak Formation.

Focused condition assessment of paleontological resources within Lake Clark National Park and Preserve (revised with cost estimate)

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