The exposure of diatomite is along one of the trail in
McArthur Burns Falls State Park. You can pay the entrance fee
for close parking or find parking elsewhere and hike in. In
either case, there is a short and easy walk along a forested
lakeside trail.
Ancient Lake Britton formed about 1.8 million years ago close to
the
Plio-
Pleistocene boundary. At that time lava flows from the
Modoc
Plateau blocked the Pit River. This natural dam flooded an area
of forest much larger than the current Lake Britton, about 120
square miles. Once formed, the lake began filling with the remains
of freshwater diatoms
(
Ancestral Lake Britton Diatomite Deposits) and other lake
deposits such as clay.
In the middle of the Pleistocene (about 20,000 to 30,000 years
ago) the Hat Creek Lava Flow (originating from near the Splatter
Cone Trail
Visit the EarthCache) covered the lake deposits. As these
basalt lava flows cooled, they contracted creating many fractures
within the flow.
Recent erosion by Burney Creek over Burney Falls
(
Visit EarthCache) eroded through the lava flow. Over time, the
falls have moved upstream due to erosion at the bottom of the falls
leaving a relatively steep narrow canyon. These steep canyon walls
were composed of the fractured basalt.
Water filled these fractures and froze, expanding and pushing
the crack wider. Eventually a piece of the lava flow was wedged off
falling down onto an ever-growing pile of rocks at the bottom of
the cliff called a talus slope
Talus slopes are important habitats for various rodents.
Logging requirements:
Send me a note with :
- The text "GC1X720 Burney Creek Talus Slope" on the first
line
- The number of people in your group.
- How large are the pieces of basalt that compose the talus
slope?
- Based on the sign near the coordinates, what does the presence
of the talus slope provide evidence for?
This EarthCache conforms to the
California State
Park Geocaching Guidelines as of the hidden date.
The following sources were used to generate this
cache:
- Splatter Cone Self Guided Trail Guide, Lassen
National Forest, Hat Creek Ranger District
- Falls Trail Nature Saunter at McArthur-Burney
Falls Memorial State Park, Video Transcript California State Parks,
2004