An appealing overview of sea movements.
Former National Ocean Service chief scientist Parker begins with the familiar: tides, which turn out to be more complicated than readers may have learned in high school. Lunar gravity pulls the ocean, but so does the sun, plus a contribution from the centrifugal force of the earth’s rotation and another from the tilt of its axis. Gravity powers tides, but geography and weather determine how high they rise. This varies from almost no tides in the Mediterranean to more than 50 feet around the Bay of Fundy in eastern Canada. The author then moves on to a discussion of more violent movements—when a river narrows as it approaches the sea, incoming tide is compressed and amplified, often producing a “tidal bore,” a destructive wave that races upstream twice a day. Parker devotes the most attention to tsunamis, which are produced by undersea earthquakes or landslides, but similar phenomena, storm surges, occur more often. Winds from tropical and nontropical cyclones can push an immense wall of water across the shore. Surges produced the 1900 Galveston and 2005 New Orleans catastrophes, but these were modest compared with those in the Bay of Bengal, which have killed hundreds of thousands. Surges, not tsunamis or heavy rains, undoubtedly gave rise to flood myths present in almost all cultures. Parker mixes hair-raising descriptions of disasters with efforts to understand them, followed by advances, mostly since 1800, in predicting sea movements, a complex process that today involves satellites, supercomputers and worldwide warning networks.
Focusing on water alone—leaving marine life to Rachel Carson and others—the author provides a lucid, original contribution to popular-science writing.