The Golden Gate Geologic Resources Inventory report, which covers Muir Woods. Image from the NPS Geodiversity Atlas
Muir Woods National Monument (MUWO) lies a few miles northwest of San Francisco in Marin County, California.
| Proclaimed | January 9, 1908 |
| Size | about 224 hectares (554 acres) |
| Protects | the last remnant of old-growth redwood forest near the Bay Area |
| The trees | more than 76 m (250 ft) tall, averaging 600 to 800 years old; the oldest at least 1,200 |
| Named for | naturalist and writer John Muir, a key advocate of the national park idea |
| Managed | as a distinct unit within Golden Gate National Recreation Area |
Its creation is seen as an important moment in early 20th-century American conservation (National Park Service 2016, 2017; Port 2016).
This page is part of the National Park Service's Geodiversity Atlas, a product of the Geologic Resources Inventory. Geodiversity means the whole range of a park's geologic and soil resources and processes — rocks, minerals, sediments, fossils, landforms and the processes that shape them — and the atlas supports education, geoconservation, and management that treats the living and non-living parts of an ecosystem together.
Hikers among the redwoods. Image from the NPS Geodiversity Atlas
The rocks
The monument's bedrock is entirely the Franciscan Complex, of Jurassic to Eocene age — a varied suite of rocks formed in an ancient subduction zone off the western coast (Elder 2013).
- How: as the oceanic Farallon Plate converged with the continental North American Plate, some Franciscan rocks were sheared and faulted into mélange — French for "mixture" — broken blocks from a few meters (yards) across to many square kilometers (miles) (Sloan 2006).
- Mélange — soft and sheared — is the monument's main bedrock; around the Bay Area it forms rounded hills among tougher Franciscan rocks.
- Chert and metachert form a large, fault-bounded block in the monument's far east, surrounded by mélange.
- Quaternary alluvium lines lower Redwood Creek.
Muir Woods belongs to the Pacific Border physiographic province and shares its geologic history and some of its formations with a region much larger than the monument.
Maps, reports and data
Geologic Resources Inventory map of Muir Woods. Image from the NPS Geodiversity Atlas
The Geologic Resources Inventory produces digital geologic maps and reports for more than 270 natural resource parks, and many products are still in progress:
| Product | What it is |
|---|---|
| Scoping summaries | records of meetings where park staff and local geologists set the mapping plan and the report's contents |
| Digital geologic maps | GIS files, a user guide and supporting map information; newer ones add Google Earth data and online map services |
| Reports | the park's setting and significance, notable features and processes, management issues, and geologic history, built on the maps |
| Posters | a PDF view of the GIS data; newer ones add aerial imagery or shaded relief. Included with the reports |
| Projects | the basics of the program and every product for a park |
- The monument's products are listed in the NPS DataStore.
- A Soil Resources Inventory for the monument is complete and also in the DataStore.
Muir Beach and the Redwood Creek restoration site from the air. Image from the NPS Geodiversity Atlas
More: Redwood Creek restoration at Muir Beach · park home · geologic time · California Geological Survey
Sources
Based on "NPS Geodiversity Atlas—Muir Woods National Monument, California," National Park Service; a work of the United States government in the public domain.
In these publicationsMuir Woods National Monument
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
1
0
0
0
Comments
