Photo: Geoffrey Day of Newburyport films waves washing sand through the south jetty last winter in February (photo by Bill Sargent).
by Bill Sargent
On December 12, 2016, I went out to North Point to see how the beach had fared during the recent king tide. So far, so good. It was the first day of an eight-day stretch of over 9-foot-high tides.
It was flat calm. Just cool green waters sliding along the riverside beach. If the weather stayed like this, we would be fine. But this was early winter in New England, where we hardly ever get eight days of good weather.
I made my way along the seaward dune of the newly completed dual dune system. It certainly looked better than a week ago when 8-foot waves were sliding up the beach face.
Workers had driven in snow fencing along the paths and roped off the front of the dunes, so people wouldn’t trample down the newly planted dune grass. It was a work of art, but hopefully not a temporary installation piece.
The jetty was a different story. The long period waves were a foot and a half, hardly high enough to be seen offshore, but they still packed enough power to move sand around when they rose up and broke on the beach.
When we see waves breaking on the shore, we usually think they are eroding the beach. But these waves were building the beach. Sand was flowing south on the longshore currents until it ran into waves refracting off the jetty.
They had created a countercurrent flowing north and together the two currents were colluding to build a 3-foot-high point of sand that jutted about 20 feet into the ocean. I watched as wave after wave washed up and over the point, leaving a wrack line of sand with shells that were darker and heavier than the surrounding sand.
Usually the waves were too chaotic to reveal this pattern, but in these calm conditions they provided more than enough energy to build up this small point of sand. But it happened almost every day with waves building this point higher and higher and welding it to the growing beach. It was also the reason there was a ridge of sand almost 5 feet higher than the jetty about 20 feet back from the jetty, but not pushed up against the jetty itself. This was part of the reserve of sand that would flow over the jetty during a major storm.
From the jetty I walked back through the dunes. It allowed me to look at the new dunes more carefully.
Workers had driven in snow fencing along new paths and roped off the newly planted areas. The low dunes blended in with the natural dunes; it was difficult to tell them apart. They were truly a piece of installation art, and hopefully not part of a traveling exhibition.
originally published in Bill Sargent’s column “As I See It” in the Newburyport Daily News