On Sunday we
went to Curley’s Cafe by Signal Hill, just down the road from Long Beach. Here
there are two nodding donkeys that get turned on to bring up oil. We discussed
the petroleum system of the Los Angeles Basin and the Long Beach oilfield,
which has over 1km of net reservoir of oil, thanks to the anticline (that’s
when rocks are folded to form an ‘n’ shape) at Signal Hill allowing oil to be
trapped underneath. Production at Long Beach oilfield started in 1921, reaching
its peak year in 1923, but it is still going strong and rates haven’t dropped
far in its nearly 100 year lifespan.
 |
| Nodding Donkey at Curley's Cafe |
We left
Curley’s Cafe at 10:20am, and drove for an hour to Crescent Bay in Laguna
Beach, to look at exposures of the Middle Miocene (around 5.3 to 23 million
years ago) Monterey Formation, which consists of shales, siltstones, sandstones
and mudstones which were deposited in a coastal setting. These types of units
are ideal for trapping oil, making them a great source for it.
 |
| Monterey Formation |
At 1pm we
went to Dana Point Harbour just to the north. We examined more exposures of
the Monterey Formation, along with the San Onofre Breccia and the Capistrano
Formation. The San Onofre Breccia was deposited in a shallow marine environment
during the early part of the Middle Miocene, and consists of sandstones with
small rocks included within it. The Capistrano Formation was deposited in a
deep water channel environment during the Upper Miocene and the Pliocene
(around 5.3 to 1.8 million years ago), and consists of siltstones and
sandstones.
We left
there at 4:40pm for a half hour journey to San Clemente Beach Cliffs, which is
where we camped for the night. We put up our tents before having a brief look
at the Capistrano Formation, but we lost focus at around 6pm when a school of
dolphins swam past in the sea! They were very cute, but not very geological!
 |
| San Clemente Beach |
 |
| Capistrano Formation |
 |
| Dolphins |
 |
| Sunset |
The Monterey Formation picture with the labels is really helpful. For us non-geos it makes it a lot easier to follow what you were studying. Shame about those dastardly dolphins coming along and distracting you though! ;-)
ReplyDeleteGlad it helped, I'm trying to keep it simple but informative! Yeah, they weren't very helpful, not that I'm complaining about seeing them! ;-)
ReplyDelete