Glacier Bay National Park and Preserve: Geology and Geodiversity

Glacier Bay National Park and Preserve. NPS.

Geodiversity is the full variety of a park's rocks, minerals, sediments, fossils, landforms, soils and the processes that shape them. The Park Service's Geodiversity Atlas, from its Geologic Resources Inventory, supports education, geoconservation and managing the living and non-living parts of each ecosystem together.

The park

• Where: Glacier Bay and the Fairweather Range, about 70 km (43 mi) northwest of Juneau, in southeastern Alaska (Hoonah–Angoon Census Area and Yakutat Borough).
• History: proclaimed Glacier Bay National Monument on February 26, 1925; re-established as a national park and preserve on December 2, 1980.
• Size: 1,328,093 hectares (3,281,789 acres) of coastal mountains, glaciers, ice fields, temperate rainforest, coastline and deep, sheltered fjords.
• Honors: a UN Biosphere Reserve (1986) and World Heritage Site (1992).
• Things to do: backpacking, birdwatching, camping, fishing, hiking, kayaking, mountaineering and rafting.

Where two plates meet

Glacier Bay sits above the collision of the Pacific oceanic plate and the North American continental plate, which drives its extreme topography and frequent earthquakes.

• The boundary: the Fairweather–Queen Charlotte Fault system, cutting across the park's western edge.
• Growing a continent: as the denser Pacific plate dives beneath North America, it slowly adds terranes — fault-bounded pieces such as island arcs, ocean plateaus or continental fragments — to the continent's edge.
• Four terranes make up the park, each with its own history of origin, assembly, deformation, intrusion and faulting.
• Rocks: layered sedimentary, volcanic and metavolcanic rocks from the Silurian to the Quaternary.

Carved by ice: tectonics raised the mountains, but glaciers sculpted them, leaving outwash plains, drumlins, eskers and fjords.

Johns Hopkins Inlet, Glacier Bay National Park and Preserve. NPS.

Maps and reports

The Geologic Resources Inventory makes digital geologic maps and reports for more than 270 natural resource parks. For Glacier Bay, products are on the NPS DataStore:

• scoping summaries — the mapping plan agreed by park staff and geologists;
• digital geologic maps for GIS (newer ones also for Google Earth and online map services);
• reports on the park's geologic setting, features, issues and history;
• posters of the map data;
• project listings.

A Soil Resources Inventory project has also begun (DataStore).

More: Glacier Bay's pages on geology, glaciers and landslides and giant waves; the Park Service's Geodiversity Atlas; and the Alaska Division of Geological & Geophysical Surveys.

Sources

Based on "NPS Geodiversity Atlas—Glacier Bay National Park, Alaska," National Park Service, citing Anderson (2017), Brew (1988), Brew and Kimball (1984) and Brew and others (1995); a work of the United States government in the public domain. The source spells it "John Hopkins Inlet."