Yes, Baja California Is Slowly Tearing Away from the North American Continent
Don't worry, you won't be around to see it.
I’m in Cabo San Lucas this week, vacationing with my family but also preparing for a dive at the legendary Cabo Pulmo, widely regarded as one of the finest diving destinations in North America. Seeing it for myself has been a long-time goal, ever since I first learned how the local community successfully fought to protect the area by helping establish a marine protected area after plans emerged for a massive resort development nearby. This effort preserved one of the world’s most remarkable marine ecosystem and helped it recover, and I’m excited to finally experience it firsthand.
Being back in Baja also reminded me of another story that has fascinated me. The Baja California Peninsula is slowly pulling away from the North American continent. Yes, you read that right .
The article below has been extensively revised, expanded, and updated, and I hope you enjoy it.
Geological forces are always at work, reshaping the planet, just usually on a timescale too slow for us to notice. Geological time. But over the long haul, they can completely transform places we think of as fixed and familiar. I’m talking about places like Southern California and northern Mexico. I’ve been down to Baja a bunch of times, including a few unforgettable multi-day kayak trips in the Sea of Cortez. Paddling past towering cliffs and snoozing on empty beaches beneath the stars. So, it’s easy to feel like the landscape has been frozen in time.
But that sense of permanence? It’s an illusion.
Baja California stretches like a crooked old finger pointing toward the southern latitudes. This long, skinny slice of land, more than 1,200 miles from Mexicali to Cabo, is full of crazy contrasts like sun-blasted deserts, jagged mountains, fruitful oases, and (sadly, disappearing) mangroves. But it’s something more than a long peninsula: it’s actually a fracture. Baja was ripped from mainland Mexico by plodding tectonic forces. The Pacific Plate drags the land both north and west, creating a gap, now filled with ocean. But it’s still moving.
Every year, Baja creeps a little farther away from the continent, slowly widening the gap. Some scientists think that, millions of years from now, the rift could widen significantly and then flood with Pacific waters, turning parts of northern Mexico and even a large stretch of Southern California into a vast inland sea. The continent is cracking apart beeanth our feet. It’s just taking its time.
This process is linked to the activity of the San Andreas Fault and other associated fault systems, which collectively form a boundary between the Pacific Plate and the North American Plate (basically everything east). The movement of these plates is very slow, occurring over millions of years.
The separation is taking place at an average rate of about 2 to 5 centimeters per year. Over millions of years, perhaps as few as five million or as many as 20, these movements accumulate, leading to significant changes in the geography of the region.
“That sub-sea level area there will eventually rip apart far enough that the rest of the Pacific Ocean, the Gulf of California, will flow in. And so it won’t just be the Salton Sea. It’ll be a permanent ocean,” says California author and geologist Donald Prothero. Imagine that. A new ocean in what is today a vast desert where we are currently hoping to mine vast amounts of lithium.
The movement of the continental crust in the area is due in part to seafloor spreading at a massive underwater seam called the East Pacific Rise. This seam stretches from the southeastern Pacific near Antarctica all the way north into the Gulf of California. Its northernmost extension, known as the Gulf of California Rift Zone, reaches close to the mouth of the Colorado River, helping drive the slow separation of the Baja California Peninsula from mainland Mexico.
“Much of it is at or below sea level because of the rifting. So it’s just waiting for water to flood in,” says Prothero. Much is already flooded. We call that area the Sea of Cortez (and we also call it the Gulf of California). The Sea of Cortez is a geologically young sea, having formed around 5.3 million years ago when the Baja Peninsula began drifting northwest.
This body of water is a critical habitat for marine life, including several species of whales and dolphins that depend on its warm waters. Being there now, I can attets that the waters are indeed warm. Jacques Cousteau, the famous French oceanographer, famously referred to the Gulf of California as “the world’s aquarium” due to its vast array of (declining) marine life.
The Sea of Cortez today is under threat from our short time so far on the planet. Overfishing and pollution, including nitrogen-rich runoff from the Colorado River, which (sort of) flows directly into the gulf, imperils wildlife. Nutrient flows can lead to a dramatic decrease in oxygen, depriving plants and animals of air to breathe. The potential extinction of the critically endangered vaquita (Phocoena sinus), represents one of the most urgent conservation crises in the region. The vaquita is the world’s most endangered marine cetacean; only a few individuals remain. This dire situation is primarily due to bycatch in illegal gillnets used for fishing another endangered species, the totoaba fish, whose swim bladder is highly valued in traditional Chinese medicine.
Habitat destruction is another growing concern, as mangroves, estuaries, and reefs, key to the survival of millions of marine species, are increasingly destroyed to make way for tourism infrastructure and coastal development. Then there’s climate change, the unrelenting buggaboo of modern life, causing sea temperatures to rise along with ocean acidification and on and on. Of course, this is all happening at human time scales.
“The Gulf of California is a temporary feature,” says Prothero. It’s a place shaped by both human impact and tectonic drift. Baja California is slowly pulling away from mainland Mexico, a process that could one day create a vast inland sea and dramatically reshape the region. While no one alive today will witness the full transformation, its ultimate impacts will be extreme: redrawing coastlines, shifting ecosystems, and isolating parts of southern California and Mexico in ways we can scarcely imagine…even though, in its own way, it’s cool to try and do so.
Have fun in Baja!
The Sea of Cortez actually used to go as far north as the Indio area but was backfilled with gargantuan amounts of Colorado River sediment. That's what we drive over from the Salton Sea to El Centro to Mexicalli and all the saline mud flats on the way to San Felipe. There are actually walrus fossils in the Borrego region!
What I find interesting is that the East Pacific Rise, an oceanic spreading center, 'snuck' under the Baja area (or was overrun by the westward drifting NA continent) yet stayed intact. This makes me wonder what dynamics are happening under California as this region also is over the northern top of the East Pacific Rise. The San Andreas is one aspect of this, shearing off coastal CA below the Mendicino Triple Junction but I wonder if more may be at work ( like the Walker Lane/Garlock fault area dynamics).