Mount Wachusett
Trails
Wachusett offers many trails that snake around the mountain and surrounding area. The trails range from 1.2 miles to 4.9 miles, but additional loops can add mileage. Wachusett stands at only 2,005 ft above sea level, and the elevation gain from the visitors center is only 600 feet, and from the mountain base is 1000 feet.
Old Indian, Stage Coach, Bicentennial trails (4.9 miles, loop): Start at the visitors center (42.491684, -71.879948). Trail is relatively flat for 3 to 4 miles, then the final stretch takes you up to the summit.
Bicentennial and Pine Hill trails (1.2 miles, out and back): Start at the visitors center (42.491684, -71.879948). Up and down to the summit.
The map below, from the Wachusett Mountain Website, depicts these trails in greater detail:
Geological History
Source: National Parks Service. National Park Service: Plate Tectonics
To discuss the geological history of Mt. Wachusett, we first explored plate tectonics. Plate tectonics is the idea that the upper layer of the earth (the lithosphere which includes the crust and the solid part of the mantel) is made up of distinct, rigid, and moving sections called plates. These plates usually include both continental crust and oceanic crust (1).
Today Wachusett lies right around the middle of the North American plate, which is moving westward at about 2 cm per year. Convection currents in the mantle move the slow-flowing asthenosphere (the next layer down of the mantle), causing the rigid plates of the lithosphere to move and collide (1).
Source: Katie Pinto and Sara Kimble North-Shore Glacial Features. Adapted from Rogers, 1985.
Because of plate tectonics, the geography of our area has changed completely over hundreds of millions of years. One common theme throughout history is that supercontinents (large landmasses of continental crust) have formed and then have moved apart. The supercontinent Gondwana formed about 550 million years ago and broke apart around 180 million years ago.
Between 550 and 419 million years ago, four chunks of crust (called 'terranes') broke away from Gondwana (3). Theses were separated from one another by faults, or significant fractures in large volumes of rock (2).
Eastern and central Massachusetts are made up of these four terranes: the Merrimack, Nashoba, Avalon, and Meguma. Mount Wachusett and the rocks in the surrounding area are part of the Merrimack terrain, dating back to the Silurian period (between 443 and 419 million years ago). (3)(4).
Since Wachusett Mountain is another example of a 'Monadnock,' we encourage you to revisit our entry on 'Mount Monadnock.' This will provide additional insight into how Wachusett came to be.
Our Findings: May 19, 2021
Much of the rock along the trail was metamorphic in flavor.
Certain outcroppings, however, seemed like sedimentary rock
Cadet Westphal checking out a turbine.
Outcropping at the summit. The rock at the top of Wachusett is called Fitchburg Complex. It is a type of metamorphic rock from the Lower Devonian era (around 400 mya) (6).
Asphalt, which makes up the roadway to the summit, is commonly made of 95% aggregate stone (usually local rocks) and 5% asphalt glue (from crude oil) (5).
We could see Mt. Monadnock (center of image) from the top!
References:
(1) Latham, J. (2021). Earth Structure/Plate Tectonics. Google Slides Presentation. Delivered in-person.
(2) Geology Terms
(3) Skehan, J. W. (2001). Roadside geology of Massachusetts. Missoula, Montana: Mountain Press Pub. Co.
(4) Wikiwand: Geology of Massachusetts