Parking is at a premium along Cliff Drive. You may need
to park a ways off and walk along the bike path to where you
can follow one of the well-worn paths down to the marine
platform near the ocean. High tides and heavy surf will make
this location inaccessible.
Numerous tubular carbonate structures can be seen exposed on the
marine terrace. These structures formed as gasses and liquids moved
through the fractures, natural cracks, in the Miocene (7-9 million
years old) Santa Cruz Mudstone. The fractures in the mudstone are
both vertical and horizontal, so the structures can be seen in both
orientations.
It is thought that the fluids and gasses
began moving upward through the sediments from organic rich
layers. These fluid and gasses had a chemistry that adsorbed
calcium from the seawater. These fluids and gasses became
saturated with calcium precipitating back out of solution as
these carbonate structures.
The fluids and gasses continued to flow through the fractures,
so the carbonate precipitated around the flowing liquid and gasses
forming tubular structures orientated along the fractures. Thus
some of the structures are horizontal while others are vertical.
Typically the central cavity of the tube can only be seen in the
vertical structures.
This process is known to be occurring in the
modern sea floor. This exposure provides insight to how
current fluids and gasses are escaping from the seafloor into
the oceans.
Logging requirements:
Send me a note with :
- The text "GC1FG0W The Toilet Bowls - Miocene Cold Seeps" on the
first line
- The number of people in your group.
- Identify a vertical and horizontal conduit and see if you can
find the associated fracture it formed in. (post a picture of each
or send me an e-mail describing your findings)
- E-mail me the diameter of inner conduit of the vertical tube
near the coordinates (No posted pictures of this particular
structure, all others are fine).
The above information was compiled from the
following sources:
- Aiello, Garrison, Moore, Kastner, and Stakes.
Anatomy and origin of carbonate structures in a Miocene cold-seep
field, Geology;
December2001;v.29;no.12;p.1111–1114;4figures;1table
- PALEOSURF: The Ancient Beaches of Santa Cruz
February 1, 2003 -- Field Trip Guide (pdf format)
http://www.es.ucsc.edu/~geoclub/paleosurfpics.html .
- USGS SantaCruz (San Francisco Bay Region 3D
image tour)
http://3dparks.wr.usgs.gov/3Dbayarea/html/SantaCruz.htm