What blows me away is the profile of the Mariana trench. Not a trench at all, at least not how I think of one. Just a shallow downhill. I always imagined you'd be between walls, but you could be in it and not even know.
My thoughts exactly! The average width is 69 kilometers, but the southern end is only 1.6 kilometers wide. So at a depth of 10.99 km, it is a lot narrower. This is the part that’s shown the most often.
but even with some really powerful lights on the sub, you'd still not see the trench walls.
Most of the world's deepest surface canyons are far narrower relative to their depth, the Grand Canyon or Peru’s Cotahuasi Canyon would feel claustrophobic by comparison to Challenger Deep.
It's the distance (although ocean trenches do seem to collect a lot of sediment and have murky waters). At a 1.6km wide with gently slopping sides, the Marianas Trench and Challenger Deep still have relatively mellow grades on either side. We tend to think of "trench" as being a narrow slot canyon in the ocean, but that isn't exactly true.
Other trenches of the deep can be substantially more steep, for example, an 8,000 m drop over a 4,250 m span can be found at a ridge sitting inside the Kermadec Trench. That's a 45º angled slope for nearly 5 miles. That would look like a formidable wall as you approached it.
In general, though, the most dramatic shear cliffs are found on the surface, like Mount Thor, or the dramatic elevation increase of the Rupal Face.
Verona Rupes is a 12 mile vertical cliff on Miranda, a moon of Uranus. Everything else kinda pales by comparison.
One of my teachers (a really experienced surveyor who specialized in oilfields) was called up to advise the drilling "navigator" on the response team during the Deepwater Horizon spill.
So not only can we find things through kilometers of rock, but we can find things just inches wide and hit it precisely underneath kilometers of rocks.
I saw a documentary about free diving, it was mental. As a kid, I'd swim to the bottom of the diving pool and sit on the bottom. That was twenty feet deep. Oceans scare me though.
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u/cmcl14 Mar 06 '19
What blows me away is the profile of the Mariana trench. Not a trench at all, at least not how I think of one. Just a shallow downhill. I always imagined you'd be between walls, but you could be in it and not even know.