OK, a recent special has been airing called “Drain the Ocean” showed various topographical features as they might appear if there were no water. At the end of the program, they gave a brief mention of the Challenger Deep.
Most of the program was pretty interesting, but I didn’t think they did a very good job on the Marianas Trench and the Challenger Deep, though. The imaging just showed a guy standing on an apparent plain that could have represented any barren area.
So, in this thought experiemnt. . .
How much of a “trench” is the Challenger Deep? If there were not water, and I stood at the bottom of it, would I see sheer walls rising seven miles high, or would I just see a gradual rise with no dramatic uplift?
Oceanic Trenches are typically 2 miles or more deeper than the surrounding sea floor.
Mt. Hood is 50 miles from my home. It’s exactly in the right height range, even with the above-sea-level elevation of the valley floor. If I were to travel 25 miles closer to Mt. Hood, and was surrounded by an unending wall of Mt. Hoods on both the east and the west of me, extending as far as the horizon, I think it would be a damn impressive sight, and totally unlike that boring thing they showed last night.
Well, kind of. Except that there would be no wall to speak of. There would be a gradual slope from your position up to the crest line where the trench meets the abyssal plain. You would see something like an elevated horizon line around 6 degrees above your horizontal 25 miles away and mostly flat, maybe slightly rolling terrain far as you could see.