Friday, June 3, 2011

The Lost Coast Found, and An Answer to Friday's Foto Mystery

Actually today's post is the answer to three questions...there's Friday's question, and these: What's the westernmost spot in the contiguous United States California? And, at what spot you can stand really close to a triple junction? All three questions are related to California's Lost Coast.
The Lost Coast is one of the few parts of California's coastline that is not traversed by either Highway 1 or Highway 101 (the area around Vandenburg is one of the others). For some seventy miles between Ferndale and Rockport, the coastline is a wilderness explored only by trails or a few rarely traveled country roads. One of these roads provides access to the small village of Shelter Cove. The other is Mattole Road, which connects the town of Ferndale with the hamlets of Petrolia and Honeydew, and then joins Bull Creek Flats Road in Humboldt Woods State Park.

Reading about the backpacking along the Sinkyone Coast and the King Range captured my imagination; how many places can you backpack to a deserted coast in California, and worry about bears (and probably Bigfoot...)? Unfortunately we didn't have that kind of time. We were in Fortuna and had five hours before my family gathering. I looked at the map, saw the looping road and "73 miles", and said to myself that there was plenty of time. Uh-huh...

The road climbs out of Ferndale, and mostly has two lanes of pavement, except for the occasional landslide that has deposited portions of the road downslope. It climbs through an attractive forest, and bright displays of wildflowers.
We were surprised by the laid back attitude of the coyote on the slope above the road. He watched us for a few moments, and then laid down for a nap...
Lupines were especially common along the road, from the highest ridges right down to the coast. Since I love lupines in all their many incarnations, this was a wonderful sight.
We crossed a series of high ridges and at least four fault zones (see the geologic map at the bottom of the post). Some of the land was forested, but much was given over to cattle grazing. The views were quite stunning. In the picture below, we had reached the valley of Bear Creek and the settlement of Capetown, which was actually a ranch headquarters and little else.
The crossing of Bear Creek gave us a tantalizing view of the beach, but we had another mountain to get over before the road reached the coast. Does it seem a bit overcast in some of these pictures? This is one of the wettest corners of the state, averaging somewhere around 100 inches of rain every year.
We crossed Cape Ridge, and dropped rather precipitously down a few switchbacks to the coastline at the mouth of Singley Creek. Here we find the answer to one of our questions of the day. Cape Mendocino is the westernmost piece of land in the contiguous United States California. It is not reached by any roads or trails that I know of due to private property (I'm open to correction on this!), but the last switchback down to the coast represents the farthest one can go in a westward direction, and is only about a quarter mile short of being the westernmost point. The rock in the photo below is Sugarloaf Island, and it lies just offshore of Cape Mendocino.
The road reaches the coastal plain and follows the shoreline for six miles or so. There are few pullouts or parking spots, but there is a wide spot in the road at Steamboat Rock that provides access to the beach and some excellent birdwatching. There were hundreds of them on the unusually shaped sea stack.
We continued rolling south along the beach and soon encountered our mystery rock from Friday's Foto Blog (that's it on the left side of the photo below). There were some great observations in yesterday's comments, and most centered on the possibility of pillow basalts, and I think that is correct (I wasn't able to get samples, so if some Humboldt friends are reading, and I'm wrong, let me know). The regional bedrock is the Coast Range unit of the Franciscan Complex, the mix of rocks that formed in the churning mess of an accretionary wedge in the subduction zone that has existed off the coast of California for several hundred million years (see the geologic map below). Most of the complex is composed of graywacke sandstone and shale with bits and pieces of materials scraped off the ocean floor, including basalts that formed at oceanic ridges. Basalt that erupts on the sea floor forms the unique pillow shaped masses. This particular outcrop was harder than the surrounding sedimentary rocks, and would have been a sea stack a few centuries ago before this section of coast was lifted up by fault activity.
With the intense amount of yearly rainfall, and the rapidly uplifted mountains composed of weak sedimentary rocks, mass wasting is inevitable. We saw a recent slump on the road. I don't envy the road crew that will be bringing in heavy equipment to fix things...
As many of you know by now, I am not the most attentive of birdwatchers, but I'm trying harder to get to know them. I had never noticed this unique shorebird before, and learned that it is called the Black Oystercatcher (Haematopus bachmani).
As we came to the south end of the beach, we saw another somewhat rare feature for northern California beaches: sand dunes. Most of the dunes were stabilized by a thick growth of grasses, but some were active.
Finally, the road turned east and UP. It was time for the climb up to the little town of Petrolia, which got its name from the distinction of being the first place in California where oil was ever produced, in 1865. It was a pleasant little village of 500 or so people. The town was badly damaged by the shaking from the magnitude 7.2 Petrolia quake in 1992, which brings us to the answer to the third question. A triple junction is a point where three tectonic plates meet. In this case, the North American Plate and Pacific Plate are separated by the San Andreas fault, which can be seen to pass the region just offshore (there were offsets here from the 1906 in San Francisco!). The San Andreas curves out into the Pacific, and just a few miles offshore meets a subduction zone that divides the North American Plate from the Gorda Plate. It is clear from the earthquake activity and ongoing mountain-building in the region that this is a focus of intense geologic activity. As far as I know, when standing on the coast here, you are standing practically as close to a triple junction as you can anywhere in the world, except for the Afar region in Africa, or at Mt. Fuji in Japan (anyone else know of triple junctions on land? It's late and my mind is fuzzy!)There is much more one can say about this road, but this is a long post already. I haven't even mentioned the Mattole River and Humboldt Redwoods, which dominate the last thirty miles of the road. Suffice to say it was spectacular. It is certainly worth mentioning that the road was not crowded. It doesn't go anywhere in particular, which means that the value of following it is the journey, not the destination. I certainly want to go back when I have some time to explore some of the corners and canyons, especially in the higher parts of the Humboldt Redwoods.

A nice road description:
Geologic Maps and Descriptions of the region:

By the way, I think this was my 800th blog post. Who figured?
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