A PALEONTOLOGIC RESOURCE ASSESSMENT OF GLACIER BAY NATIONAL PARK AND PRESERVE, SOUTHEAST ALASKA – PROVIDING DATA FOR FUTURE GEOLOGIC MAPPING

Glacier Bay National Park and Preserve, at the northern end of Southeast Alaska, constitutes a spectacular array of mountains, tidewater glaciers, and fiords. This area was one of the first places from which fossils were reported in Alaska. However, with the exception of the Cenozoic sediments in the Lituya Bay area, most of the Park has been subject to little subsequent paleontologic study. The area of Glacier Bay proper is composed primarily of Paleozoic rocks of the Alexander terrane, an exotic tectonic entity that appears to represent a rifted shelf margin of Siberian origin. Five formations were established by Rossman (1963) in the Glacier Bay area: (1) Willoughby Limestone (late Silurian); (2) Tidal Formation (late Silurian); (3) Pyramid Peak Limestone; (4) Rendu Formation; (5) Black Cap Limestone (Early and Middle Devonian). An unnamed Permian limestone unit has been recognized by D.A. Brew and others in subsequent geologic mapping. Only the Willoughby Limestone has yielded significant fossils collections in Glacier Bay. Both the Pyramid Peak and Rendu formations are unfossiliferous. The Devonian age Black Cap Limestone and unnamed Permian age limestone unit both appear to be relatively fossiliferous, but their fossils remain poorly known. Quaternary glacial deposits in Glacier Bay also include well-known fossil forests.

In contrast, the Lituya Bay area, along the outer Pacific Ocean margin, consisting of Cenozoic age rocks of the Yakutat terrane has been much more intensively studied in terms of its stratigraphy and paleontology. Numerous localities are rich in marine bivalves, gastropods, and echinoids.

An in-depth paleontologic assessment is in progress to document all known fossil localities within this park unit. This effort is intended to provide baseline information for future geologic mapping within the park, and to focus researchers on areas needing additional studies, as well as to document and protect its paleontologic resources.