A couple of interesting bits of geology in the
Santa Barbara area are the methane seeps
just off the coast near Coal Oil Point and the
Gaviota Wind Caves. The methane seeps are the
result of deposition of sediment with lots of dead
plankton 6-18 million years ago, which became oil
and gas -bearing sedimentary rock. The rocks were
uplifted and fractured by tectonic forces about
one million years ago, which brought the oil and
gas closer to the sea floor, and some of it seeps
out through cracks, though about 99% of the
methane is broken down by microbes before reaching
the surface of the water.
In the 80's Arco put metal tents over
the some of the seeps to "harvest" the methane and
sometimes collected a million cubic feet of gas
per day, but oil extraction reduced the
pressure in the oil and gas reservoirs so not as
much comes out anymore. Carpinteria also got
its name from local seeps which produced tar
that the Chumash used to seal canoes. When the
Spanish came, they determined that the area was
the Chumash's "carpentry shop" or "carpinteria".
You can find a lot of information about the seeps
The Gaviota Wind Caves are less well
documented, but they are interesting to visit if
you are up for hiking, or there are nice photos
online. They are in sandstone from the Oligocene
just west of the 101 where it turns to the north.
Their formation is not entirely certain, but it is
likely that salt that gets into the air from sea
spray was deposited on the rocks and grew crystals
that weathered larger and larger divots into the
rocks. The bigger the holes get, the more salt can
be deposited in them, and the more the rock is
Another interesting feature in southern
California is the tufa at Mono Lake. This
is not as close by, but they are worth noting.
Mono Lake has no natural outlets. Water
only leaves by evaporation, which causes the water
to become concentrated in dissolved carbonate.
When spring water rich in calcium flows in through
the lake bed, the calcium and carbonate react to
form limestone around the spot where the spring
water comes in. This eventually builds up
underwater tufa towers.
Starting in the 40's the city of Los Angeles began
diverting water from Mono Lake's tributaries,
causing the water level to fall. This caused a
number of environmental problems, but it also
allows us to see the tufa, which is now exposed.
Environmental activists eventually won protections
for the lake, so the water level is beginning to