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Baja Geology Rocks!

TANGAROA anchored near fantastical formations

Voyaging along the western coast of the Sea of Cortez is akin to being in the Grand Canyon looking up at colorful layers of rock piled atop one another. But instead of our boat floating down a mighty river, Tangaroa is cruising on a dynamic and relatively young (geologically speaking) sea. One of the real joys of living aboard our Maritimo M51 is being able to tuck into coves carved into the shoreline. We drop the anchor, the view from our “house” now a different one from the day before.

It’s experiences like this that make living on a boat so cool! (Make sure you read to the bottom of this post! You won’t want to miss the short video at the end!)

The Sea of Cortez (also known as the Gulf of California) lies between mainland Mexico and the Baja Peninsula, the slender sliver of land extending roughly 775 miles south from its border with California to Cabo San Lucas. While it’s only 30-150 miles in width, the Sea is incredibly deep. When we cruise from Marina Puerto Escondido, near Loreto, out to some of the many islands that dot the coast, it’s not uncommon to see the depth finder just…stop. At first, we thought something was wrong with the equipment but realized that, when there’s thousands of feet of water below Tangaroa’s keel, the depth finder signal just doesn’t reach to the bottom. The sea floor is an incredibly deep basin created by fantastic movements of the earth’s crust.

We’ve been exploring primarily between Loreto and La Paz

The unifying theory of plate tectonics, which I find quite thrilling, explains both these deep Gulf basins far below our hull to the towering layer-cake rocks high above the helm. (This landscape excites my inner naturalist but I’ll refrain from too much of a geology lecture!) What’s important to this story is that plate tectonics explains the movements of the earth’s crust, which is broken into pieces called “plates,” and describes how the plates interact with one another, which is what happened to create the Baja Peninsula and this stunning Sea. When I look upon geologic features, I feel the Earth changing as plates move about, their very positions affecting so many factors in our lives. To me, geology is alive!

While we cruise along this dramatic coastline, I think about tectonics and how plates collide causing great mountains to build or deep ocean trenches to form. In the lava layers we see, I think of the volcanoes that rise & erupt causing the earth to tremble. Plates move apart from one another as ocean basins grow & expand, pushing land masses away from one another or rifting the very continents apart. Plates slide past one another, fracturing & faulting the crust. While you’ve been reading this blog post, plates have moved ever so slowly, changing the face of the earth as we see it at the speed of a fingernail’s growth.

Plate boundaries. Notice how continents are part of a plate!

And Baja is part of that movement and change. Like a book, the rock layers are pages that record the physical, chemical, and biological processes happening when that layer was being deposited. I wish we had a good guide to the geology of this region to better interpret the layers we are seeing: greens, reds, white, tan, & brown layers color the landscape. We can see where tectonic activity has caused the layers to buckle and break and where volcanoes once laid down lava layers.

Multicolored layers attest to the regions active geologic history

Once upon a time the Baja Peninsula was part of the Mexican mainland. Like the well-known San Andreas fault in California, Baja sits right on the boundary of two plates that are sliding past one another. Sometime around 6 to 10 million years ago, this fault began ripping the thin sliver of land that we now call Baja away from the rest of Mexico. These processes are still underway and the Baja Peninsula continues to be on the move at the geologically lightening fast speed of roughly 5 cm (2 inches) per year. The Peninsula continues to move west & northward, ho! Rifting, rupturing, and rerouting created this dramatic body of water we’re exploring. We can’t feel the plates moving; we just feel the wind and waves that affect the sea. But its the geologic features of the Sea that create the winds and waves we feel. It’s the geology that affects the wildlife for which this beautiful & bountiful sea is famous. Geology is the bones upon which life thrives.

You can see the fault lines and areas where the crust has spread in this image of the Sea of Cortez seafloor.

We love watching how the changing light alters the colors and textures of the mountains rising high above the blue sea, green fields of cardon cactus, and white beaches. Rosy red in dawn’s light, these layered Peninsular Range peaks form the backbone of the peninsula. Uplifted and eroded Jurassic to Cretaceous Age rocks (200 – 60 million years old) rocks, their core is part of the part of the same rocky structure forming much of the Sierra Nevadas.

Sierra peaks and lava-capped hills rise above cardon-cactus fields

Down here, it’s the impressive Sierra de la Giganta mountains we see all along this stretch of coast. The dramatic layers that make up the mountains formed between 25-17 million years ago during volcanic eruptions that laid down the various lava and ash layers. When these volcanoes were active and spewing forth the ash & lava, this land was still attached to the Mexican mainland. It was only many millions of years after the lava flows had cooled and the ash layers hardened that rifting began, separating Baja from the mainland. During the millions of years it took as Baja sheared off the mainland and drifted west, massive amounts of sediments eroding from the mountains were deposited into the rift.

Dramatic peaks of the Peninsular Range Sierra de la Giganta tower above colorful rocks in a beautiful cove

These sediments, turned into rock layers, have been lifted up to become the peaks we see. As rain, rivers, and wind erode the peaks new sediments pile up into sand dunes or create the beautiful beaches we see as we cruise through the area. Our favorite anchorage is one of the most geologically spectacular along this stretch of coast. The Sierras rise high in the background while rich red rocks rise into rounded hills above a blue cove. Nowhere else do we see rocks like these. We took our Highfield tender ashore to explore further and discovered fine bands in the rounded rocks. The geology here reminds us of ancient sand dunes and layered red rocks we’ve seen in the Utah deserts.

Fine bands in the red rocks look like sand dunes turned to stone

With this cove as a convenient halfway spot between Loreto and La Paz, we enjoy making it our stopover to witness it’s dramatic landscape. Like the ever-changing geologic landscape, the view from our floating, comfortable & well-appointed home changes with each new sunrise and sunset. We couldn’t ask for a better place to be than aboard Tangaroa! Join us for a visit to our favorite anchorage: the stunning red rocks and cactus forest of Puerto Los Gatos:

Tangaroa anchored by the rich red rocks of Puerto Los Gatos

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