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    Re: Tycho Brahe Mars oppositions
    From: Frank Reed CT
    Date: 2004 Dec 4, 00:38 EST
    Fred H wrote:
    "but I believe the rate of sedimentation from a
    big river such as the Mississippi, Amazon, Rhine, etc, can be fast
    enough to change the tidal frequency in enclosed bays, such as Fundy,
    over periods of thousands of years."
    Yes, there will be changes in small areas. That's very true.
    "This would be a shorter time scale
    than what I envision for the "geological time scale," which I see as
    ranging between tens of thousands to tens of millions of years.  Now
    whether these changes in tidal frequency in local bays would have a
    significant effect on global tides is an additional question."
    Very little effect.
    "However, the ice ages would have had a profound, global effect on tidal
    modulation of the earth's angular momentum.  The end of the last ice
    age was rather sudden, but the onset depended on accumulation of snow
    over extended periods, and would have been longer, I expect: imagine
    building a mile thick sheet of ice at the rate of 20 inches per year."
    The global tide pattern would have been roughly the same even with sea level so much lower. The tidal friction would have been lower since the shallows over the continental shelves would not have existed. How much, I don't know...
    The geophysicists who worry about these matters talk about changes in tidal braking occurring over the very-long geological time scale and that the changes arise from re-arrangements of the continents and ocean basins themselves.
    Frank R
    [ ] Mystic, Connecticut
    [X] Chicago, Illinois
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