Posted by: coastlinesproject | June 12, 2017

Plum Island. The Survey

Chapter 38

The Survey

April 28, 2017



On April 28th Plum Island was engulfed in a cold gray shawl of fog. I couldn’t see Salisbury. I couldn’t see the ocean. I couldn’t see any sign of another human being. This was a problem because I was supposed to meet Paul Croft’s students from the Essex Tech school at 10am.


So I decided to walk out to the end of the jetty just to make sure. Halfway there I spotted the students intently inspecting the wrackline. What had they found? I took a few more steps and watched the students magically morph into a flock of fog-enshrouded seagulls. These conditions sure weren’t going to make it easy to survey the jetty.


But a moment later the fog lifted just enough so I could see a spot of sunlight on the far shore. Then it got uncomfortably warm. I was still wearing an anorak I had put on to fight the morning chill, now it was just  oppressive.


I figured the fog was so thick that Paul had cancelled the field trip so I decided to return to my car and get rid of my coat. I also knew there was a big fat juicy chicken salad sandwich I had been saving for just such an emergency.


But as I walked back through the dunes I started to hear disembodied voices floating up from the beach. So I yelled through the fog.


“Are you from Essex Tech?”




“Great! I’ll meet you at the end of the jetty in a few minutes.”


That gave me just enough time to ditch my coat, take a swig of water and gobble down my sandwich before looking for the students in the fog. When I found them, a marine biologist was giving them an impromptu talk about marine debris, so I had a chance to catch up with Paul.


He had already briefed the students and separated them into three groups. Each group had to evaluate the situation and figure out the best way to survey the jetty to see how fast it was settling.


It was a difficult problem. You had to assume that everything on the beach was unstable and that some parts of the jetty were settling faster than others.


I joined a group that wanted to set up their survey equipment on several of the larger boulders and sight from them to a stationary navigation beacon. Then they planned to flash a laser at the beacon on the other side of the river. The problem with this solution was that the students had to make sure the survey equipment could be set up at exactly the same height on its tripod legs when they repeated the measurements.


The idea was to get one solid measurement to use as baseline data in June, and then take another measurement when school started again in the fall. Then, if all went well, they would retake measurements every month during next winter’s erosion season.


The second team had decided to place the survey equipment directly on the boulders to avoid the difficulty of setting up the tripod legs at exactly the same height for each measurement.


The third team had come up with the idea of measuring from the boulders that were settling fastest, back to the boulders they appeared to be more stable. Even though the entire jetty was settling this method would measure the dip where the jetty was settling faster. It could also been done in a thick fog!


By the end of the day each team would have enough data so they could debrief the other teams and decide which method they would use when they returned to make their real measurements in June.


It had been an instructive day and I knew the rest of my sandwich was waiting for me back in the car. What I didn’t know was whether to eat it after it had been sitting in the sun, which had finally deigned to come out. So I decided to eat it anyway, and paid the price that night.





William Sargent’s recent book, Plum Island; 4,000 Years on a Barrier Beach, is available in local bookstores and at




Bill Sargent will be leading Storm Surge beach walks starting from the Plum Island Point lighthouse Sundays at 2pm. Cost $10.










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