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From: dpw@bonnie.UUCP (David P. Williams)
Newsgroups: net.physics
Subject: Re: A couple of old Physics puzzles
Message-ID: <342@bonnie.UUCP>
Date: Sat, 5-Jan-85 18:29:08 EST
Article-I.D.: bonnie.342
Posted: Sat Jan  5 18:29:08 1985
Date-Received: Sun, 6-Jan-85 01:12:37 EST
References: <327@bonnie.UUCP> <47@rti-sel.UUCP> <333@bonnie.UUCP> <50@rti-sel.UUCP> <245@petrus.UUCP>
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Organization: AT&T Bell Laboratories Whippany NJ
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Within the last year or so, I have seen a relief map of the world's ocean
bottoms produced on the basis of radar altimeter data from a satellite.
The rub is that the radar signal could not penetrate the ocean surface!
The altitude data from many orbits were combined to produce topographical
maps of all ocean surfaces.  Then, the shapes of seamounts, shelves, and
other features necessary to pile up the overlying water (through
gravitational attraction!) were determined.  As I recall the distance
from peak to trough for the combined ocean surfaces was on the order of
100 feet - the highest point was on a continental shelf and the lowest
was in mid ocean.  The source of the map was Aviation Week and Space
Technology or one of the science mags.

So, add to the factors that cause the difference in level between the
Atlantic and Pacific at the Panama Canal gravity and the shape of features
along the isthmus.