>    Rising sea levels may or may not also be affected by rising land masses? Frinstance, does the rising of the Mid-Atlantic ridge tend to "push" more sea water toward the opposite shores? Does the rising in the "Ring of Fire" (volcanic activity along the Pacific) tend to "push" water toward other more dormant areas?
>        Of course, it all happens fairly slowly---but don't these rises tend to complicate estimates of the total rise in sea level?
>            Q-Man

Yes.  Calculating an absolute sea level change is very difficult.  Our best ideas are based on measurements of areas that do not appear to be moving up and down on their own, and for very recent changes we can use satellite data as well.  High levels of submarine igneous activity does indeed promote high sea level.  This is specualted to have been important in the Cretaceous and part of why you can find Cretaceous marine mollusk fossils throughout the middle of North America.

    Dr. David Campbell
    "Old Seashells"
    Biology Department
    Saint Mary's College of Maryland
    18952 E. Fisher Road
    St. Mary's City, MD  20686-3001 USA
    [log in to unmask], 301 862-0372 Fax: 301 862-0996
"Mollusks murmured 'Morning!'.  And salmon chanted 'Evening!'."-Frank Muir, Oh My Word!