Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site bonnie.UUCP Path: utzoo!watmath!clyde!bonnie!dpw 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> Distribution: net Organization: AT&T Bell Laboratories Whippany NJ Lines: 17 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.