Here's a relief map of the sea floor - with the vertical scale exaggerated for clarity. But the Monterey Canyon really is on a *massive* scale: walls 1,700 metres (~1 mile) high & by the time it reaches the Pacific’s abyssal plain, it’s run out from California's coast for over 400 kilometres. 2/
I was just out there doing a survey last week. It's an amazing place.
Thanks. You’re going to make me go down another rabbit hole. In case you don’t hear from me again…
It's not far off being as impressive as the Lomonosov Ridge (which I'm still amazed isn't better known) - bsky.app/profile/mike... But it’s right under the noses of millions of Californians & visitors, unknown to many of them, because of all that fun blue stuff that’s currently in the way. 3/
Courtesy of the Monterey Bay Aquarium Research Institute and Scientific American, this is what they’d see if those thousands of vertical metres of ocean hiding it from view suddenly drained away: www.youtube.com/watch?v=jgfk... But how did it get this way? 4/
In another parallel with the Grand Canyon, it seems to have been carved out by a river... And that river is *still flowing*, under thousands of meters of ocean! Welcome to the weird & wonderful world of UNDERWATER RIVERS. 5/
“Rather than flows of fresh (or at least salty) water, undersea rivers are slurries of silt and sand that cascade along channels on the seabed. Each particle tumbles through the water under its own weight. A new river starts on the continental shelf like an avalanche in the mountains..." 6/
."...picking up speed & momentum as it moves until it flows like a liquid. Once started, an undersea river can flow for weeks & even months at a time, moving the same amount of sediment in one go than all the world’s land-based rivers transport in an entire year." www.bbc.co.uk/future/artic... 7/
But it's not just Monterey. There are undersea rivers all over the world! Here's the coast of Portugal, where an undersea river flows down a narrow channel inside the five-mile-wide (8km) Nazaré canyon, running out to reach the Atlantic abyssal plain nearly 2.5 miles (4km) beneath the surface. 8/
Fantastic thread. Nazare Canyon creates what is widely considered the largest wave on earth. Current record for wave successfully surfed is 93.73 ft.
If you enjoy big-wow sciencey stuff like this, you may enjoy my science newsletter, Everything Is Amazing! everythingisamazing.substack.com It's totally free to sign up. 9/
Such a shitty place to put such amazing work. Get off the Nazi newsletter site, please!
Seriously, @mikeachim.bsky.social - they’re super shitty even if you don’t care about the Nazi thing:
And finally, thanks to everyone at the Monterey Bay Aquarium Research Institute, whose terrific research I relied upon when putting this thread together: www.mbari.org/know-your-oc... (Everyone working in the Earth Sciences: you deserve better than what's happening to science funding right now.)
And if you enjoyed *that* thread, here's another mindblower of a story I covered a while back: bsky.app/profile/mike... Thanks for reading!
⭐️ Thanks! Very interesting. Do you happen to know of any good sources for info about mapping underground rivers in the land-locked Midwest?
Is there a way to see if there's a linking point from monterrey to the Marianas trench?
Their geological origin stories are actually very different! bsky.app/profile/mike... Plus they're a *long* way apart...
Reason I asked was the earthquake in Russia and the tsunami hitting America, and all recent seismic activity could impact on the ring of fire.
Elkhorn Slough is the terrestrial expression of the uppermost part of the canyon; during previous ice ages, much more of the canyon was exposed. My understanding is that geologists theorize the canyon was carved by outflow from CA’s Central Valley in the Pleistocene, before the Golden Gate existed.
Thank you for this, Christina! Fascinating.
See, for example: agupubs.onlinelibrary.wiley.com/doi/full/10....
my favorite one of these definitely has to be Hudson canyon! I could read BOOKS about it, omg. Offshore topography is so interesting when you consider the pieces that weren't always below the water within the context of wider earth systems over long periods of time!
Wow, my Dad was stationed there when I was very young. Where I live in Scotland, the middle of our loch is over 80 meters deep. Gotta love the glacier action!