By Graham Giese
Some years ago - well to be honest, many years ago (it was in 1956) - I visited the U.S. Coast and Geodetic Survey office in Washington, D.C., to learn as much as I could about the technical details of a major survey of the outer Cape Cod coast carried out under the direction of Henry Marindin (born Henri Louis Francois Marindin in Lausanne, Switzerland) during the summers of 1887, 1888 and 1889. I was familiar with Marindin’s reports - they were printed in ponderous old government volumes stored on the shelves of the Marine Biological Laboratory library in Woods Hole. In reading them, I had been surprised to learn that the “direct objective” of his work had been “to provide a base for future comparisons, which will be of value to geologists and others who study the changes in the coast-line.” I was excited about the possibility of repeating Marindin’s survey.
The good people at USC&GS were at first somewhat bemused by the idea - the 19th Century survey was very “low-tech” by comparison to their current aerial photogrammetric mapping methods - but they soon got into it and suggested a plan for a resurvey, one that was eventually used successfully. They also urged me to look over the historical records of the Marindin survey stored at the National Archives, and made arrangements for my visit.
As a result, I found myself entering that impressive classical building on Constitution Avenue where security, even then, was remarkably tight. I was assigned a small brightly-lit office and boxes of carefully itemized papers and artifacts were brought. There was much more than I could look at in the limited time available, but I saw enough to mentally reconstruct a fascinating episode of Cape Cod history. My notes from the visit were lost as I changed jobs and moved over the following years, but here’s how I remember it …
The crew had travelled by railroad, arriving at the Orleans station in 1887 with their precious theodolite and other instruments and supplies. I know that their tents came with them, because I read an irate letter written by Marindin the following winter in which he complained about their wretched surplus Civil War tents which leaked badly.
But many of their basic requirements were purchased or rented locally, such as the dory used for offshore depth sounding, and the horse and wagon used to transport the party and supplies to their beach encampments as they slowly worked their way from Chatham to Provincetown. In another angry letter, Marindin expressed dismay that the USC&GS accounting office would not accept the small charge for stabling the horse over the winter period between field seasons.
Some of the surveyors’ most important requirements were freely available. They used existing structures, such as lighthouse foundations and prominent natural boulders, as bench marks to preserve the critical elevations above sea-level that they had painstakingly determined. Eastham cartographer and scholar, Steve Mague, has researched and published a report describing Marindin’s bench marks. One of them is on Doane Rock, the large glacial erratic dominating the Doane Rock Picnic Area in Eastham. If you look carefully, when the sun is low and the shadows long, you can make out the letters, “B. M.”, cut into the face of the rock on July 14, 1888, by one of the party.
Today, in order to better understand complex coastal processes in an era rife with climate change concerns, my colleagues and I at the Center for Coastal Studies are still comparing the information provided by Marindin’s survey with contemporary data as he foresaw we would. And while present-day airborne surveys can map the contemporary coastal form in a time span more like three hours than three years required in the 1880’s, Marindin’s carefully acquired measurements provide our only reliable map of the outer Cape Cod coastal form as it was more than 120 years ago.
Our comparisons reveal that over the intervening time, the shores of the outer Cape both retreated and grew. Most of the outer coast eroded at a long-term annual rate that increased southward. Beginning in the Provincelands, about half a mile east of the Old Harbor Life Saving Station and continuing south to Chatham, the retreat rate increased from about three-quarters of a foot to five feet per year. However, west of the eroding section we find long-term accretion all the way to Race Point Light. In this section, long-term annual shoreline growth reached as much as five feet a year – thanks to sand brought by waves from the eroding shores to the south.
-Graham Giese is a coastal geologist residing in Truro. He serves as Senior Scientist at the Center for Coastal Studies in Provincetown.