From this overlook, if you look south along the beach at the bottom of the cliffs you will see some interesting rock terraces, which are in fact ancient seas floors which have been formed into marine terraces. These terraces are thought to be created by a combination of powerful forces.
The first force is the sea itself, which helps to create the flat, relatively smooth tops via the relentless pounding of the ocean's waves. During glacial periods, the sea level drops considerably and water retreats, only to advance again as the Earth warms, and that action creates wave-cut marine platforms.
The second force is seismic. Here in Santa Cruz, the Pacific Plate, part of the "Ring of Fire", is moving northward, while the San Andreas Plate is moving southward, combining for about two inches of movement per year. Nervous local geologists began studying the movement in the era of the 1906 earthquake, and for a time there was a beacon on top of Loma Prieta that was used to measure the mountain's extremely rapid (in geological terms) movement.
Locally, these two mighty plates meet at the where there is a bend in the San Andreas Plate around Loma Prieta, and as a result the Pacific Plate is slowly forced upward over the San Andreas Plate. This uplift activity creates the Santa Cruz Mountains and lifts these marine terrace layers upward as well. The uplift is approximately .3mm per year.
The Santa Cruz area comprises five such marine terraces. If you look at most of Santa Cruz, you'll notice that it's a relatively flat landscape separated by steep bluffs from the adjoining terraces. Other marine terraces can be found along the California coast and beyond, the oldest (and highest) being approximately one to two million years old.
The Seymour Marine Discovery Center here is a great place to come with the family. They offer daily tours. Admission to the area is free and open to the public but the museum itself charges admission. Please check their website for current information on hours.
To log this cache there are two requirements (Revised 2/3/07) - Please read them carefully!:
- Take a picture of yourself, holding your GPS, at the location and post it along with your log. I must be able to tell from the picture that it's you at the location (no background of just sky from now on) to verify that you were there.
- Go to the railing of the overlook, and face south. Take a good look at the marine terraces here. In your log or in email to me (your choice) you must estimate how high the cliffs are above the flat terrace rocks below. If you do not, I will be forced to delete your log. This educational aspect is required for all EarthCaches and this one would have been archived had I not added this requirement.
If for some reason you can't immediately post the picture, post your log as a Note rather than a Find until you have done so. Finds logged without the exact requirements being posted within a reasonable amount of time (like a day) will be deleted. You can't say you weren't warned, right? :)
Bibliography and additional reading:
- James F. Tait, Coastal Geology of Natural Bridges State Park
- Jennie Munster and Jennifer W. Harden, Physical Data of Soil Profiles Formed on Late Quaternary Marine Terraces near Santa Cruz, California
- Colin Pinney et al., Soil Chemistry and Mineralogy of the Santa Cruz Coastal Terraces
- California's Marine Terraces, an excerpt from the California Coastal Commission's California Coastal Resource Guide
- John V. Young, Ghost Towns of the Santa Cruz Mountains
Content revised 7/8/05
Bonus info! Did you notice the old weathered remnants of a mast on the edge of the cliff there behind the discovery Center, just a little south of this Earthcache? I found some history about it from the datasheet for the nearby benchmark, in an entry from way back in 1931: "A SHIP WAS WRECKED ON THE BEACH ABOUT 30 FEET S OF THE STATION. A MAST SAID TO BE USED FOR HOISTING THE CARGO FROM THE WRECK IS STANDING UPRIGHT ON THE EDGE OF THE CLIFF S OF THE STATION. THE TOP OF THE MAST PROJECTS ABOUT 10 FEET ABOVE THE TOP OF THE CLIFF."