Greyhound Rock: Where’s the Hound?

Does Greyhound Rock look like a hound to you? Photo: Lauren McEvoy/Mobile Ranger
Does Greyhound Rock look like a hound to you? Photo: Lauren McEvoy/Mobile Ranger

Greyhound Rock is named for the beach’s large rock formation that sits stoically offshore in the crashing waves. Usually, the rock is connected to the beach by a small sand spit that is part of the Greyhound Rock State Marine Conservation Area near Davenport, north of Santa Cruz, California. The rock was given its name by a Santa Cruz pioneer named Thomas Majors who thought it looked like a hound.

Historic photo of Greyhound Rock. The beach shows much more sand than it typically has these days (in winter or summer). LAUREN CAN YOU GET DATE FROM YOUR MAH NOTES?
Historic photo of Greyhound Rock. Photo: Santa Cruz Museum of Art & History

Today, it’s a bit hard for most people to see the hound. Perhaps, over the decades, the ocean surrounding Greyhound Rock County Beach has eroded away any canine resemblance. If anything, the rock looks like a sleeping alligator from above, and from down on the beach, it just looks like a long mound of layered mudstone. That’s very cool in and of itself, hound or no hound.

Hound, alligator, or chocolate soft serve ice-cream? You decide. Photo: Lauren McEvoy/Mobile Ranger
Hound, alligator, or chocolate softserve ice cream? You decide. Photo: Lauren McEvoy/Mobile Ranger

Formation of the “Hound”

Greyhound rock is made up of Santa Cruz Mudstone. This is the rock formation that shapes the landscape characteristics of the northern Santa Cruz coast, from the north county line (basically at Ano Nuevo State Park) through to the west side of Santa Cruz. It’s a fairly hard rock type, although its many layers vary in their hardness and how easily they erode. If it were a much more erodible rock or did not have layers, the coastal landscape we see today might be without the many arches and bridges and dramatic sea cliffs with their undulating pocket beaches.

Santa Cruz Mudstone in front of Long Marine lab. A great example of "pocket beaches". Photo: Mobile Ranger
Classic shore platforms and pocket beaches of the Santa Cruz Mudstone. Long Marine Lab. Photo: Julia Gaudinski/Mobile Ranger

The pocket beaches occur where the horizontal layers of the mudstone have fractures or “joints” running roughly perpendicular to the cliffs. The joints are points of weakness, so the waves erode along the joints much faster than the rest of the layer.

Creation of Santa Cruz Mudstone

The Santa Cruz Mudstone was created about 7 – 9 million years ago (late Miocene era) by the settling of fine-grained silts, clays, and silicate remains of billions of single-celled plankton called diatoms. It varies in thickness but has been measured to be 8,900 feet thick in at least one location.

The Santa Cruz Mudstone at Waddell Bluffs.
Santa Cruz Mudstone at Waddell Bluffs. Photo: Julia Gaudinski/Mobile Ranger

The sediments accumulated offshore of the ancient (Paleo era) coast in ocean water about 450 – 600 feet deep. The silts and clays came from nearby rivers. Because the amounts coming from each source varied over time, so did the composition of the layers. With time, these sediments became very thick. This is nearly the same conditions we have today half a mile off our coast.

Arches and bridges tend to form in the Santa Cruz Mudstone. Photo: Julia Gaudinski/Mobile Ranger
Arches and bridges tend to form in the Santa Cruz Mudstone. Photo: Julia Gaudinski/Mobile Ranger

Hardening to Rock

Over millions of years, thousands of feet of sediment were deposited on top of the Santa Cruz Mudstone sediments. With burial, the sediment warms up and some of the silica from those billions of diatoms dissolves and later turns into cement that binds the particles together. This is called lithification.

During and after lithification, the sediments are also subjected to regional tectonic stresses from huge tectonic plates moving around, which can cause folding and faulting. Thus, the original sediment composition, the degree of lithification, and the amount of tectonic stress combine to determine how hard a rock is and how it will erode. In and around Santa Cruz, the Santa Cruz Mudstone is not very deformed, with just some tilting, jointing, and faulting.

Take the Self-Guided Mobile Tour

This piece is part of the Santa Cruz Marine Protected Areas Beaches Tour made possible by the Santa Cruz Collaborative with support from the California Marine Sanctuary Foundation and the Resources Legacy Fund. Download the free app with many tours of the Santa Cruz area and beyond.


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About The Author

Molly Lautamo is a content strategist and writer in Santa Cruz, California. She loves exploring and researching her surroundings and then writing about her discoveries to inspire others to get out and explore too. You can check out more of Molly's writing at

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  1. Frank May

    Your articles are excellent and enjoyable. Years ago when I was researching something I’ve long since forgotten I ran across a thesis at the U.C. I thought it was very interesting. The author proposed that Drakes Bay in Marin wasn’t really where they had landed but, instead, down around an nuevo. The article referenced ship’s log records, etc. for support.

    Does anything like that sound familiar to you?


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