Home
Map
Browse Map
Explore away
Explore Map Collection
Check out our basemaps
Print a Map
Plus
Generate a high-quality PDF
Field Guide
Field Guide
Discover local flora, fauna, geology, and more
Local Flora & Fauna
Learn the ecology of your area
Local Geology
Learn the geologic formation at your feet
Get Started
or
Sign In
Welcome
Sign up to start exploring the one-of-a-kind Natural Atlas Topo map
Continue with Apple
Or
Sign up with Email
Already have an account?
Sign In
MAP
Topo
Waterfalls
Rock Formations
Campgrounds
Trails
Boat Launches
National Parks
State Parks
Scenic Spots
Measure
You must upgrade to measure routes
Start Free Trial
0 ft
Max
0 ft
Copyright
© Natural Atlas
| Roads, Buildings
© OSM Contributors
|
Data Sources
Topo
Ecoregions
Public Lands
...
BASEMAPS
Default Weather
Temperature
Smoke
...
WEATHER
Flows and clastic rocks, undifferentiated (ORTfc;0)
Geologic Formation
in
OR
Print Map
Generate High-Quality PDF
Lithology
Andesite
Conglomerate
Andesite
Other
(3,972 mi²)
Geologic Age
Miocene (23.03 Ma – 5.33 Ma ago)
Geologic Unit Label
Tfc
Chiefly basaltic andesite and andesite lava flows and flow breccia containing plagioclase and pyroxene (hypersthene and augite) phenocrysts, mudflows (lahars), and volcanic conglomerates; locally includes some dacite flows. Includes lesser, coarse- to fine-grained epiclastic volcanic sedimentary rocks and ash-flow and air-fall tuffs. Partly equivalent in age to unit Tba and may be partly coeval with younger parts of unit Tstb. Locally altered adjacent to larger intrusions. The oldest radiometrically dated rocks assigned to this unit are about 17 Ma (Sutter, 1978); in part lapped by flows questionably assigned to unit Tba, radiometrically dated at about 10 Ma, and unconformably overlain by flows of unit Trb. Includes some of rocks formerly mapped as Sardine Formation and some mapped as Rhododendron Formation
—
USGS
Taxonomy
Classified As
Geologic Formation
Search
Search the outdoors
Map
Plans
Field Guide
Community
My Profile
My Trips
0
My Field Notes
0
Notifications
More