Travels in the Northern Hinterlands of California

The holiday season often means the special moments with family and decorations and Santa Claus, but when your family is spread out in a thin line running the entire length of the west coast of the United States, it also means some time on the road. We have had a long way to go in the past few days, but we stopped a few times and took in some of the extraordinary geography of California's isolated north coast.

Getting to the coast from our home in the Great Valley requires crossing the Coast Ranges first. Our preferred route is through the Clear Lake region. Clear Lake itself is a huge natural lake formed by lava flows and landslides that altered and blocked water course flowing into the Russian River. It covers 68 square miles, which makes it the largest natural lake entirely within California (Lake Tahoe is larger, but is partly in Nevada. The prominent peak on the lakeshore (above) is Mt. Konocti (4,721'), which is a potentially active volcano with eruptions as recent as 10,000 years ago. Hot springs and earthquakes attest to the continued existence of magma chambers in the region.

We reached the coast in the vicinity of Eureka and Arcata and headed north on Highway 101. We soon passed an incredible sight at Humboldt Lagoons State Park. The growth of hooked spits (long linear sand bars) has led to the formation of a series of baymouth bars which isolate the coastal estuaries from the open sea (there are no big rivers in the immediate area to flush out the sand. The bars are only a few hundred feet wide at most and one extends for three miles. There are a total of four lagoons.

The lagoons are a unique ecosystem. Because they are breached only on an irregular basis, salmon and other creatures have adapted in interesting ways. Young salmon migrate downstream to find their way to the sea blocked. They live in the lagoons for extra months or even years, gaining size that may enhance their chances of survival in the open sea. On the other hand, breeding salmon may have difficulty getting into the estuaries.

Soon we were deep into the Redwood forest. The Coast Redwood only grows along the coast of California and in a tiny part of southern Oregon. They are extraordinarily large with the giants reaching heights of nearly 400 feet. They are related to the Sequoias of the Sierra Nevada, and the Dawn Redwood of China (and ornamental landscapes). The Redwoods are the tallest, but the Sequoias have the greater bulk. The Redwoods make for excellent lumber, while the Sequoias do not. It was almost their undoing.

The Redwoods once existed as an unbroken forest from the Big Sur Coast to Oregon, topping out at some 2 million acres. More than 90% of the old-growth forests were cut down during the last century, and it was only through the foresight of the founders of Save the Redwoods and other organizations that old-growth groves were purchased and given over to the state of California for permanent protection from logging. As recognition grew of the need to preserve not just patches but entire ecosystems, Redwood National Park was established in 1968 and expanded in 1978. It protects an entire watershed (Redwood Creek) that has old-growth forests as well as second-growth tracts.

We didn't have very much time, but we stopped at Humboldt Redwoods State Park, and at the visitor center for Redwood National Park as we passed through. We hated to move on, but a storm was coming and our families were awaiting our arrival. One could spend weeks among these beautiful trees and the stunning coastline. Which we intend to do as soon as possible.

Vagabonding on Dangerous Ground: A Geologist Walks Onto a Bar in Cascadia...

A very strange-looking sandbar at Big Lagoon in Humboldt Lagoons State Park on California's north coast.

A geologist walks INTO a bar. She may get hammered, vulcanized, laminated, stoned, cemented, bombed, or petrified. And all her drinks will be on the rocks...

But when that geologist walks ONTO a bar, she just gets sand on her feet.

Yeah, yeah, I know, shut up and stick with the science...

We're traveling north on a journey through the Cascadia Subduction Zone, exploring this unique region with an eye to the geology, and the beauty, of the region. We've explored the Redwood forests of the Eel River, and the Lost Coast where the Cascadia zone begins. Today we are looking at a unique state park along the coast north of Eureka, California, and south of Crescent City. It's called the Humboldt Lagoons State Park, and the three lagoons found there are bounded by stunning examples of baymouth bars.

Big Lagoon at Humboldt Lagoons State Park (source: Google Earth)

One of the reasons that the already infamous Cascadia Subduction Zone earthquake might not be as bad as it could be is that so few people actually live on the coast of Washington, Oregon, or Northern California. Why is this? If one looks at a map, one notes the paucity of flat lands along the coast. There are sometimes some coastal terraces and a number of small natural harbors, but for most of the distance between Vancouver Island and Cape Mendocino, the mountains rise from the sea. There's no place to build. That's not to minimize the tragedy. There will be horrible results, but the largest cities like Seattle and Portland are inland, behind the coastal ranges, and they will be spared the worst of the tsunami damage, if not the shaking. There are certainly a number of towns along the coast, but there are also long stretches with few people. One of the lightly populated stretches of coast is between Eureka and Crescent City.

Big Lagoon at Humboldt Lagoons State Park

Along Cascadia's mountainous coast, wave action is violent and constant, and cliffs are quickly worn back, forming a relatively straight coastline. But there are also a number of drowned river valleys and coves, many caused by the rise of sea level after the last ice age. There are four small examples of these valleys at Humboldt Lagoons (one of which was filled in to allow some farming). But the coastline is very straight. Why?

Intense rainfall sends sediments down the many rivers and streams, and vast amounts are added to the coastal waters. When waves encounter the coast at an angle, the swash and backwash of the water causes sediment to be transported along the coast, a process called longshore drift. There is a tremendous amount of sediment in this coastal system.

Humboldt Lagoon also include a county park at the south end of Big Lagoon. It's a nice place to see coastal erosion!

When waves hit rocky coasts, they expend their energy wearing away at the rocks. When those same waves reach a cove of open water, the wave energy is dissipated as the waves spread out. When sand is being transported around the headland and into a cove, the declining energy causes the sand to settle into a curving sandbar, called a hooked spit. The spit may grow large enough to close off the mouth of the bay, becoming a baymouth bar.

In most bays along the Cascadia coast, rivers are large enough to keep the bays open, but at Humboldt Lagoons only small streams are present. Water can simply seep through the sandbar rather than flowing out. The bays are breached only during the wettest, most intense storms. The baymouth bars are miles long, and incredibly straight (see the Google Earth image above). They don't look natural, and yet they are.

Smaller Stone Lagoon is just north of Big Lagoon.

The lagoons are a fascinating spot along the north coast, and they get a bit less attention than Redwoods National Park and the state parks. They are an important link in the ecosystem of the region, and are marvelous spots for birdwatching and looking for other animals. If you ever travel that way, the state park (and associated county park) is well worth a visit.

The next stop on our vagabonding tour of the Cascadia Subduction Zone is Crescent City at the far north end of California. We'll have some things to learn about tsunamis in California.

The Other California: Baymouth Bars - It's 5 O'clock Somewhere?

It's Friday, the end a long week! I'm home from a four day exploration of the California's North Coast country, and it was...uh...academically stimulating? Uh, a teacher's exploration dream? Er...a wonderful excuse to escape the heat in California's Central Valley? Yeah, that's it. We have to be honest here. But that doesn't mean I wasn't paying attention.

I haven't been up in the Crescent City - Eureka area all that much, and I am delighted to discover something new every time we pass through the region. Today I am offering pictures of some of the finest baymouth bars I've seen in California. Coming around a corner of Highway 101, one is struck by a line of sand so long and so straight that it almost seems artificial, but it most certainly is not. It is the baymouth bar enclosing Big Lagoon, a fresh-to-brackish body of water separated from the Pacific Ocean by a three-mile-long strip of sand that is no more than a few hundred feet wide. This lagoon and several others are protected in Humboldt Lagoons State Park.

One might wonder how a strip of sand can survive the constant battering by the powerful waves that constantly rip away at the coast, but it is actually those very waves that bring out the creation of the bars. Waves expend the full brunt of their energy against headlands, but the energy is dissipated as waves enter into coves and harbors (which is, of course, why boats shelter in coves). Sand is carried along the beach by longshore transport, where waves wash up the beach front at an angle, but flow directly back into the water. When sand along an uneven coast encounters one of these bays, the loss of wave energy causes a spit (a long thin sandbar) to develop.

If there are no large rivers flowing into the bay, the spit will eventually reach all the way across the bay opening, forming the baymouth bar. The water behind these bars is fresh or brackish, and seeps out through the sand bar. It is only when there are flooding events or particularly violent waves that the bar is breached, and a portion of the lagoon pours into the sea. These are important ecological moments because the lagoon may have numerous salmon fingerlings and juveniles just waiting for a chance to get to the open sea.

I was trying to find a spot to get a good shot of the Big Lagoon, and we discovered a nice little county park at the south end of the bar. County parks sometimes have less than altruistic reasons for existence, and I suspect that might be the case here. Yes, there is a wonderful long beach with tables and a small boat ramp and all, but you may notice there is also a paved road that quite literally dead-ends at the top of the seacliff. The fury of the waves in this part of California exacts a heavy toll on beachfront property, and I can't be sure, but there very well could have once been houses here. Cliff retreat has to be considered in landscape planning, and a nice beautiful park fits the bill when housing developments would probably fall into the sea.

Still, if you are a southern Californian or Floridian, it might seem strange to see a vast beach with barely a dozen beachgoers. True, it's not as sunny, but this is the way I like my beaches!

The picture above is Stone Lagoon, another of the lagoons in the state park.

A Google Earth shot shows Big Lagoon from above, if you had trouble visualizing what a baymouth bar like.

The Other California is my continuing series of articles describing geologically interesting places in our wonderful state that somehow miss showing up on the postcards. Check them out!