This wiki page says that the average slope of the undersea Hudson Canyon is 1.5 degrees.

that's what I saw, but it's the length of the canyon. We're looking for the sides.

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It says "At this point the canyon is as much as 12 km (7.5 miles) wide (from east rim to west rim) and as much as 1,100 m (3,609 ft) deep from canyon rim to canyon floor across the continental slope." So, if it's in the middle approx., that'd be 1,100/6000, or 18.3%

The Grand Canyon "ranges in width from 4 to 18 miles (6.4 to 29 km) and attains a depth of more than a mile (1.6 km)," but I'm not sure how deep it is at that narrowest point. Still, using worst case, it's at least 1/9, or 11.1%, probably higher.

This page from the park service shows a graphic that seems to indicate that Hells Canyon is about 10 miles wide, with a slope of maybe 5632/(5*5280) or so, about 21.3%, possibly higher--it looks like the west rim overlooks are closer than five miles to the river. I'll dig out some more topos.

I just thought of something. The Black Canyon of the Gunnison is extremely deep and narrow (so named because sun don't reach the bottom ), so narrow that it doesn't much qualify under the "at least a mile" restriction. But the canyon walls rise almost straight up from the river, so a mile down river would be a gradient over a mile. At Chasm View, the rim is 1820 ft above the river, so to a mile downriver that'd be a gradient of 1820/5280, or 35.5%.


PS: Half Dome "rises more than 4,737 ft (1,444 m) above the valley floor." I'm pretty sure you can get a mile away from it, so that's 4737/5280, or 89.7%. That second photo sure makes it look like you could get within a mile of it, on the valley floor.

not bad. Half dome IIRC is actually the top of a mountain and not level with anything else.



I'm still imagining some place steep like a canyon but that leads up even higher once out of the canyon.

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KAIBAB PLATEAU in northern Arizona its elevation of 9,241ft, (2,817m) above sea level.
or POINT IMPERIAL at 8803' it overlooks the desert of the east of the grand canyon the highest point of the grand canyon is 6600' above the Colrado river!

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But, the question is, what is the gradient?

I have found an answer that I'll accept. If anyone gets this answer or one that beats it they win.


hint? mountain near a plane.

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Is the gradient greater than 90%?

not near

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Doesn't Half Dome beat it then?

The one I'm thinking of goes higher within a 1 mile radius.

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Is it in the Indian Ocean?

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no, but if you find one with a larger gradient you win.

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So the gradient is greater than 90%?

PS: maybe I don't understand your objection to Half Dome. Could you explain that some more? ths

sure. half dome does the rising over a very small lateral distance. it is not the gradient I am looking for, but one over a mile distance.

There are places on earth that rise higher than half dome, but they take a little sideways motion.


The question as stated is

if half dome was within 1 mile of a higher peak then that higher peak would actually be closer to correct than half dome.

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No, I computed that 89.7% by assuming that we were starting a mile away from Half Dome. If we were to start at the "bottom" of Half Dome, the gradient would be in the thousands of percent maybe.

PS: I found this online map of Yosemite. It looks to me that Mirror Lake at 4098 feet elevation is almost exactly a mile (lateral distance) from the summit of Half Dome at 8836 feet elevation. That's (8836-4098)/5280, or 89.73% grade.

None of the elevations listed on that map are higher than Half Dome.

Here is a grade calculator
http://www.csgnetwork.com/inclinedeclinegradecalc.html




so, you're saying that you cannot find any place on earth that rises more than 4800 feet within one mile?


doesn't the grand canyon beat it at a mile deep?

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When you said "not near" I thought you meant that the place that you're thinking of had not near as much as 90% grade.

It's more than that, and underwater?I don't know. At Grand Canyon village (cite) where it is nearly a mile deep, it is 10 miles wide. So, on average it's not, but it could be greater than 90%, depending, but I haven't found anything that supports a figure greater than that. There are lots deeper canyons in the world, but very few of them are even as steep as the Grand Canyon.

Monterey Canyon?

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C'mon guys, this is a pretty