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.
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