A surprise gift from a brother on a recent birthday was Jonathan White’s 2017 Tides: The Science and Spirit of the Ocean, a surprise twice over: once, to receive something at all as, at advanced birthdays we expect little and hope for health.  The other surprise was how engrossing it was, how much I learned. Science and personal experience at its best.  New knowledge about long observed phenomenon tumble into the brain like tide-washed stones.  Just a wonderful book!

He begins with tidal bores — those surfable waves created when great incoming tides meet great outgoing rivers.  The Bay of Fundy is the most famous (on which I’ve surfed a muddy boat,) but there are many more.  Qiantang, China, southwest of Shanghai, has been known for millennia — and I just found out about it! (Another thing about birthdays of later years — each one reveals how much more we do not know.)  There is even an annual festival to watch the “Silver Dragon” come roaring by at spring, full moon. Thousands have died underestimating the height and speed of its incoming waves.

From there we find out that not only are tides linked to the moon — now taught in second grade or so — but how wonderfully many and wonderfully complex the links are –and the wonderful names they have    I’ve already impressed seagoing friends with my command of perigean syzygy — and you can too! (It’s that very high tide when the sun, moon and earth are aligned and the moon is closest in its orbit to the earth.  You did know the orbit of the moon is an ellipse, not a perfect circle, right?)  And if earth is at perihelion — when its orbit is closest to the sun– well, the tides get even higher.  If a storm is pushing in a surge … well you get it.

You will become secure in the difference between neap tides and spring tides (which are not related to the spring.)  Nice line drawings and diagrams help us see these relationships, anchor them in our own marshy minds..

Beginning with the grounding of his own boat at high tide in Alaskan waters, and scary ebb, leading to near disaster, he laces all chapters with nicely done personal observations and reminiscences — scrambling up the sea wall seconds ahead of the Silver Dragon, braving the 16 knot current of the Magellan Channel.  (That’s fast!  The current through Raccoon Straits in San Francisco Bay hits 5 knots at flood tide, against which kayakers have a very tough time.)  He goes to Mavericks with big-wave surfers and under big ice at low tide to pick oysters with Inuit, Lukasi Nappaaluk.  In France, along the Normandy coast, he watches forty-five foot tides turn a Benedictine monastery into an island and then leave it high and dry, twice a day.

He finds time for science, in the best way:  Galileo observes that water sloshing in jugs on a moving boat must be like tidal sloshing on earth; Issac Newton’s formidable math describes gravity and tide theory; Pierre Simon-Laplace –the Newton of France– forges the beginnings of modern dynamic tide theory.

Tidal clocks in the DNA of mud shrimp enable them to time their advance and retreat to the advance and retreat of their covering tides.  Sloshing tides are slowing the spin of the earth through the friction of their back-and-forth.  As our days grow longer (by about 2.3 milliseconds a years (one million years from now a day will be an hour longer) the moon moves farther away — an inch and a half per year (9 1/4 feet during my life time.) In fact, in the early years of the moon, it was one-quarter or more the distance closer.

As we read we are loosened from our naive notion that rising and falling tides are like the filling and emptying of a bath tub, steady and even. Moon, sun and earth have regular, if predictable effects on bodies of water with different sizes, bottom conditions, wind and barometric pressures, bigger or smaller rivers emptying into them– all of which contribute to local variations of tides, which are components of the world-connected oceanic waters, beneath which the earth moves.  Let this stagger your mind: it is not the tide coming up to meet you, it is you turning to meet the tide.

Mankind has  long been aware of the moon and tides. Moon calendars on etched bone have been found from 25,000 years ago.  In oral history trickster Raven saves ‘the people’ with his knowledge of tidal times.  Coastal folk could predict fishing and bi-valve plucking hours weeks ahead of time.  They knew that tides rose and fell twice unequally, one high tide higher than the other.  Some people knew no tides because they barely existed.  In fact, to our surprise, there are places on earth where tides do not exist.

He closes, as he must, with climate change and rising seas –“From Kuna Yala to Venice.”  Even here, he doesn’t overwhelm us with statistics and numbers about approaching disaster. He visits the Kuna people on the biggest of the hundreds of San Blas islands along the North-east coast of Panama where, yes, they are threatened by sea-level rise but first he is a guest at a coming-of-age ceremony and, why not,  he takes the opportunity to introduce us to early, and imaginary, tide-prediction machines.

Anyone who’s dabbled in tidal pools, watched the tide advance or retreat over a summer beach, been sailing or snorkeling,  scanning  tide-tables for  arrival or departure times, or perfect versus impossible swimming, will find something to like, and learn, in this book.

Science writing at its best.

I want to read it again, but it’s already being passed on to others.  Now, if Jonathan White would just continue his research into tides:  how do sun, moon and earth combine to affect the tides of air around us, the tides of fluids in us, the imperceptible surging of the continents below us, and the liquid, tidal, fire of earth’s inner core?  Fascinating stuff.

 

Thanks to brother Ken for thinking to send it to me

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