Standing at the end of the small Acadia National Park peninsula known as Great Head, it would be easy to miss the three bronze discs embedded in the pink granite underfoot.

As one of Mount Desert Island’s easternmost points, Great Head offers a sweeping view of the entire Schoodic Peninsula as well as hundreds of smaller geographic extravagances and eccentricities: the Porcupine Islands, Egg Rock Lighthouse, Winter Harbor, to name a few.

It is, in short, a surveyor’s dream — which brings us back to those weathered bronze discs.

They are called benchmarks, and engraved in each are the year they were set (1934), the name of the spot (Great Head) and also the name of the national agency that lay them 80 years ago: the U.S. Coast and Geodetic Survey.

A bronze disc set into the granite on Great Head in 1934. Along with two other discs, it once helped mapmakers triangulate their location.
PHOTO BY CHARLES EICHACKER

Formed by Thomas Jefferson in 1807 and now part of the National Oceanic and Atmospheric Administration (NOAA), that agency was tasked with creating a national network of surveyed reference points. The work began on the Eastern Seaboard, but by the 20th century the UCGS had moved inland.

Some of the benchmarks, like the ones arranged in a triangle on Great Head, comprised triangulation stations that would allow someone with topographical maps and datasheets to determine the distances to other stations. Such markers could have spared mapmakers and rusticators traveling up the Maine coast 60 years ago lots of trouble.

These days, GPS systems have eliminated the need. But that doesn’t mean you can’t still hunt the benchmarks down. In fact, Penobscot resident, mapmaker and outdoor enthusiast Jane Crosen has made it her hobby to do so. Crosen looks up the locations of benchmarks on websites such as Geocaching.com/mark, where coordinates are logged and like-minded explorers post details to help find them.

In the datasheet Crosen printed out for the Great Head benchmarks, for example, were indications that an observatory had once stood nearby. Indeed, when you make it out to the point, there is what appears to be a rubble pile less than 20 feet away.

But on Great Head, as with many other benchmark locations, much of the joy of finding them is in the journey. To get there, you park in the Great Head parking lot off Park Loop Road. The 1.4-mile Great Head Trail then moves in a loop around the peninsula.

Heading counterclockwise around that trail on a quiet spring afternoon, the blue-blazed trail initially passed through a dense forest of spruce and pitch pine. But as the route starts angling upward, you hit several groves of paper birch. The sounds and smells of seawater crashing soon emerge. To the south, you start seeing Acadia’s pristine Sand Beach, where on nice days people swim and play volleyball.

The Great Head Trail skirts past Sand Beach, a popular Acadia destination in summer. A separate trail forks down to the beach.
PHOTO BY CHARLES EICHACKER

A trail even forks down to the beach, but with traces of snow on the ground, this wasn’t sunbathing weather. Still, the beach made for a lovely site as the trail turned into a granite field.

Take heed: both Crosen and the man who literally wrote the book on Acadia trails got momentarily lost at this point. Steve Perrin, author of “Acadia: The Soul of a National Park,” hiked the Great Head Trail after a blizzard in 1992.

“Guessing at the route, I once found myself on top of a cliff where the trail evaporated beneath my feet,” he wrote. But Perrin backtracked and found his way, just as Crosen did while serving as guide for this reporter.

Anyone who perseveres up the brief incline there is in for a treat: the views open up not just onto the beach below, but also to adjoining seaside cliffs and the iconic Beehive Mountain to the west.

The trail then hooks around the peninsula, offering views of crashing waves, diving eiders and a world of shrubs and lichens. In summer, wild blueberries also grow along the trail.

Soon, you see that debris field where an observatory used to stand. With a bit of searching, you’ll see three bronze discs too.