Natural Bridges State Park

Natural Bridges State Park Santa Cruz, CA

Although this State Park is dubbed "Natural Bridges", in 1989 the Loma Prieta earthquake caused a portion of the bridge to collapse, much like another bridge forged from steel, and return to the sea. Therefore the "bridges" are no more and all that remains is a lone sea arch that was once connected the the headland. The photos to the left and below (taken from www.parks.ca.gov and a mystery source) show the dual bridge status once hailed by the park.

As stated in a previous post, sea arches are formed when waves break at the tip of a headland and the wave energy is directed around both sides of the land mass. The beating waves tear away at the rock and form parallel sea caves which eventually meet, thus forming the arch. As the salty sea water continues to erode away at the promontory, the arch falls and becomes a sea stack, and then eventually becomes sand. By examining the sand of any beach, one can determine the make-up of the surrounding rock and in some cases the geographical source. For instance, the sand at Ocean Beach in San Francisco, is made up of granite from the Sierra Nevadas! Millions of years ago the Sacramento River, carrying sediments from the mountains, emptied directly into the San Francisco Bay. The sediments were then carried by the the California Current and deposited at the beach, forming large dunes which have historically fed and kept the site rich with sand. Present-day Ocean Beach is removed from the California Current due to the geography of the bay, and the ancient sand dunes are depleting without being replenished. In time, Ocean Beach's vast sandy expanse will be no more. But, I digress.

Natural Bridges State Park is also home to a mythical "Monarch Natural Preserve" Mythical, because like the eroded sea arch, the butterfly mecca too has been emaciated. While the grove is full of fragrant eucalyptus trees, I only spotted two of the orange stained-glass patterned insects. While the State Park's website touts a presence of nearly 100,000 butterflies each winter, santacruz.com reported only 1,000 in 2009. Sadness!

And now for something completely different!

On this rather warm day in February, I collected an Ostrich-Plume Hydroid along the shoreline mixed in with various types of kelp (bull whip kelp, feather boa kelp, etc.). When I first examined the specimen, I thought it was a type of sea algae or maybe a type of lichen. However, after scouring books and websites, I could not identify the creature so I sent my photo to algaebase.com and was told that this guy is a carnivorous hydroid. I was way off! Hydroids are in Phylum Cnidaria along with jellyfish and sea anenomes. The feathery-like appendages are actually colonies of polyps. Like other cnidaria, the ostrich plume hydroid's polyps contain strong stinging cells which can cause irritation and rashes to the unassuming swimmer or snorkler. However, when I found the hydroid, he was already long gone of this world. RIP Ostrich-Plume Hydroid.


Photos= Joshua R. Neely (with exception of the aforementioned State Park photo)