While walking along the inner edge of a salt marsh the other day, I stopped 1 stopped to watch a finger of the incoming tide poking its way up one of the dry creek beds. It seemed like something alive, inching and probing forward, twisting and sliding among the interlaced ripple channels, veering off to one side and then the other, halting momentarily as though coiling and gathering strength, then striking out in a long, slow, sinuous glide for several feet.
Looking more closely, I saw that the lengthening, watery digit was populated. A hermit crab was scuttling about near its tip, a small marsh shrimp clambered over the sand grains just behind the crab, and behind the shrimp some sort of long, thin marine worm weaved its way along – all encased, like the organelles in an amoebic cell, in this moving, transparent finger of water.
The tide, advancing across the flats and up creek channels, often does this, creating numerous temporary marine aquariums, spreading out, for our approval and investigation, more organisms than we could assemble with a good deal of time and effort. Similarly, when it recedes, it often leaves its collections of shells, plants and dead animals in the channels between the ripple marks, laid out neatly in parallel rows as though on museum shelves.
I played with the hermit crab a little, prodding him with my own finger to the very limit of the advancing tidal probe. He appeared frustrated that he could not run ahead any faster than his medium of escape was progressing, and tried to retreat, only to be blocked by a dark swatch of seaweed. I tossed him a few inches ahead of the moving channel and he stood there, rocking indecisively, as though he did not know his way back to the water and had to wait for it to catch up with him.
As I stood watching these creatures trapped within the thin, probing edge of the tide, the finger itself ceased to advance and stood there, marking tide, as it were. This was high tide, marked and underscored with a precision and definiteness impossible on the rhythmic, oscillating shores of the outer beach. It was as though the water itself pointed and said, ‘Here I stop – no further.’
After no more than a minute, it began visibly to withdraw, leaving a narrow, winding, moist trail in its wake. I had that sense, as Emily Dickinson once did in the presence of the withdrawing tide, that we live, or survive, at the indulgence of some great global courtesy, a net of seemliness or manners thrown over the earth’s blind and wrathful forces, a primitive lust of the sea for the land checked by some overriding decorum that we call the regularity of the tides.
And then I saw, for the first time graphically, that strange property of the tide born of planetary inertia. Even as the long finger of the tide withdrew back down the creek bed, innumerable bits of seaweed and other marsh debris continued to be carried forward inside it, like a separate flow of arterial blood. The tide has two separate components, one vertical – which we call the rise and fall – and the other, less obvious and horizontal -which is known as the ebb and flood, or current, of the tides.
The first of these two motions is caused by the bulge of the ocean’s waters outward toward the moon (and to a lesser extent, the sun). The second motion is the apparent backward and forward movement of the water as the earth’s ocean floors turn beneath it. The extremes of the rise and fall motions are called high water and low water, while the turning point between flooding and ebbing currents is known as slack water.
In the open sea, these two movements are indistinguishable. But in harbors, estuaries and flats there may be up to an hour’s difference, or lag, between high or low water and slack water. Thus, on our shores, the tide actually begins to fall while it is still flooding, and to rise while it is still ebbing. Yet only in certain protected places, such as the upper reaches of tidal creeks, can the interaction of these two great natural forces be observed so distinctly, unconfused by the competing spectacles of waves and crashing surf.
If this double movement of the tides sounds complicated to us, it can deceive its inhabitants as well. Treacherously, silently, appearing to continue inland even as it withdrew, the finger of tide had moved out, stranding the creatures it had carried in with it. The hermit crab stood with a puzzled air, the shrimp began some ineffectual burrowing, and the worm writhed out its life on the wet sands.
Anthropocentrically, I chose to save the crab (it has ‘arms’) and tossed it several yards downstream. But when I looked again at the ‘worm,’ I saw that it was actually a pipefish, a relative of the seahorse and a common inhabitant of eelgrass beds where its eellike body is invisible among the waving grass stands. I picked it up and tossed it along with the crab, and then, just to be catholic, threw the prawn after as well.
I am fascinated by all of the various ways the tides approach our shores: the small, relatively inconsequential fluctuations of Vineyard Sound, the strong, treacherous rips and channels around Monomoy and Woods Hole, the greater height and heaving advance of the Outer Beach, and the impressive sweeps and withdrawals across the wide flats of Cape Cod Bay. Yet whenever I think of the tide it is always like this, as a slow-moving finger of shallow water across grooved sands. I think it must have something to do with the first time I saw the tide come in -I mean the first time I saw it, and sensed in its inanimate force that our shores were something alive.
It was in Provincetown Harbor, one summer night many years ago. I was walking the dark shore with a friend, a large, affectionate man with a child’s passion for showing people things. We walked in half-lit shadows, behind the Crown and Anchor Inn, in the sallow naked glow of the building’s backlights, with the muted noise of whatever dance music was in fashion that season blaring in the background. All at once my friend stopped, pointing down at our feet, and said, There it is.’
I stopped, too, looked down, and jumped back in alarm, as though a basket of snakes had been spilled out at my feet. It did look like snakes – small, sliding serpents of black water, twisting and thrusting and sidling across the dark sands, intertwining, separating, and finally coalescing to the rear as it ate up that beach under the piers in small, advancing nibbles. I could not have been more startled and amazed than if I had witnessed the famous tides of Southern France that come in over the flats with the speed of a race horse, or the incredible Amazon tidal bore, a moving waterfall twenty-five feet high and several miles long that moves up the river at twelve knots for some three hundred miles, with a roar that can be heard inland for fifteen miles.
There are times in our lives, decreasingly so as we get older, when we seem peculiarly open to certain impressions. No one can predict these times, nor can we always successfully analyze them afterwards, nor does the force of the impression necessarily bear any proportionate relation to the object that made it. Just why the tide impressed me so that night I do not know. But it has stayed with me ever since, so that when I think of the tide – as I might think of God or Communist China or some other large abstraction – it is not as some great lunar heave and splash of the planetary bathtub, or as some massive, rising inundation, or as any other of its more majestic and dramatic incarnations; but as an intimate running and feeling of water snakes and water fingers across dark sands, an intricate consumption of the land by water, a loving and almost passive tracing of the earth’s contours by the advancing sea, taking on those contours, flowing into her curves and edges, even as it obliterates them.
Somehow, in this gentle movement of the tide across the ripples and channels of the flats, I sense the advance of whole oceanic waters across the continental shelf, roaring silently through submerged canyons, across drowned plains and river valleys, taking bends and turns along our crenulated shorelines, funneling up into bays and estuaries, spilling through channels and sinking into holes – so that it meets itself hours apart on either side of Monomoy’s thin spar, and with heads so different at each end of the Canal that it creates currents in excess of eight knots every six hours in alternating directions.
Over the years I have watched these delicate fingers of tide push their way along, slowly and thickly, in and out, like summer and winter. So fragile do they seem that I can change their course or block their passage momentarily with my own fingers, as we easily melt the first snowflakes of winter on our palms.
Yet they have behind them the power and inevitability of suns and satellites in their orbits, the force of the world’s oceans and the mass of the moon. The actual drops of water in their deft, searching tips may have come in no more than a few hundred feet offshore, yet they have the knowledge of all drowned earth in them. This soft tidal probe is infused with the running of thousands of miles across unknown complexities of terrains, the visible resultant of an untraceable intercourse between seabed and sea-heave. It is the moving finger of universal forces that writes, here on these shallow summer sands – inspired, passionate holy water.