Sandstone caves in Castle Rock formations
Sandstone caves in Castle Rock formations
Mountain Biking Highlight
Recommended by 7 mountain bikers
This Highlight is in a protected area
Please check local regulations for: Mount Diablo State Park
Location: Contra Costa County, California, United States
5.0
(1)
10
01:22
14.0km
260m
4.0
(1)
13
03:03
28.7km
800m
2
04:09
49.4km
980m
Water, wind, and calcite erosion in per-volcanic sandstone formation.
Slightly acidic rainwater seeps into the sandstone during winter rains and dissolves some of the calcite. Warm and dry days cause the moisture to pull the dissolved calcium back out of the rock, causing holes and caves to form.
Watch for peregrine falcons and other birds of prey nesting high up in the Castle Rock caves.
The upper trails are closed Feb-July to avoid disturbing the nesting birds.
June 16, 2016
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Location: Contra Costa County, California, United States
5.0
(1)
10
01:22
14.0km
260m
4.0
(1)
13
03:03
28.7km
800m
2
04:09
49.4km
980m