Links to the guides for the self-guided geologic hikes are at the bottom of this page. The guides below were last updated in January 2024.
About the hikes:
The compilation of self-guided geologic hikes in the Fells is an outgrowth of my interest in informing the public about the exciting field of geology. The geologic hikes in the Fells introduce the fundamental geology of the Fells along with some of their details. They are an excellent way to introduce natural science. I am especially interested in informing middle through high school students and their teachers about local geology, but anyone can learn Fells geology. Really curious younger students may also find the geology of the Fells interesting. I have also been struck by the curiosity that many hikers in the Fells exhibited, when they saw me in the field.
Aside from the geologic mapping required, it took about 8 years (beginning in 2016), working off and on, to assemble all the self-guided hikes currently available. In the planning stages are also a versions for phones or tablets with GPS capability and an online video version. This will take a while! We (my students and I) periodically revised the guides to improve readability and directions in the field and to also update and correct the geology as my field work continues.
The hike segments posted here are a trial balloon. I hope you have fun with them, and I would be grateful to have feedback on what you think of them. Feel free to email me at: jack.ridge@tufts.edu. I would be glad to answer your questions and make the hikes more informative. Take advantage of the special geologic explanations that are available as of 2022.
Please be respectful of the rules in the Fells. Stay on the trails and do not collect or deface rocks. Leave them unblemished for others to see. Also, do not leave any trace, and if you feel inclined, please be a sport and pick up trash as you go.
The hikes in the Fells went through several revisions, which continues, and I had my students test them out before going public. They also helped improve the writing, from the technical style I use for my research to one that can be easily digested by the public. They have also improved my use of commas, for which I am severely challenged! I would like to thank the undergraduate students at Tufts who trail-tested and helped revise the self-guided hikes during the summers of 2018, 2020 and 2021. This includes Brandon Levenstein, Rose Malanga, Jenna Mello, Jason Theal, Eli West and Lara Williams. I would also like to thank the Department of Earth and Climate Sciences at Tufts University for its support on this project.
Have fun!
Jack Ridge
Downloads of The Hikes
Below are the currently available downloads of self-guided geologic hikes in the Fells. At the beginning of each download document (PDF format) is useful information about what to expect while hiking in the Fells and also some fundamental geology to get started. Each hike route is on DCR trails and they are marked on geologic maps in the guides. Take advantage of the special geologic explanations linked below.
Special explanation pages:
The special explanation pages provide additional and more detailed explanations of things introduced in the self-guided tours. Links in the guides also shortly lead to these explanations. Here are the available explanations:
How do granite plutons form?
How are Ages of Rock Formations Determined using Radiometric Dating?
What is an Unconformity?
The hikes that are currently available:
The Skyline Trail (7 parts) – west of Rt. 93
The Rock Circuit Trail (3 parts) – east of Woodland Road and across southeast Fells
The Crystal Spring Trail – north of Pond Street to Whip Hill
Virginia Wood – south of Pond Street in Virginia Wood
Lawrence Woods – loop from Medford High School
The Skyline Trail – Geology of the western Fells. The Skyline Trail hike is in seven segments that form a 10 mile (16 km) loop. The hikes are most informative, and easier to understand and follow, if they are done in order. At the beginning of each hike is information about how to connect to the starting point of each hike and in some cases alternate starting points and routes.
Here is a link to a short video I narrated for the Friends of the Fells on part of the Skyline Trail on Gerry Hill (Skyline 2 below): Rock Formations of Gerry Hill: Rocking in the Middlesex Fells – YouTube At the time this video was made the Westboro Formation in the Fells was called the Virginia Wood Quartzite. Recent revisions of the map and new radiometric ages indicate a correlation of the Virginia Wood Quartzite to the Westboro Formation.
NOTE: On previous versions of the guides the Westboro Formation was called the Virginia Wood Quartzite. The Virginia Wood is now known to be part of the Westboro.
Skyline 1 – Bellevue Pond to Red Cross Trail: [Link to: Skyline1-BellevueRedCross-SelfGuide.pdf]
Skyline 2 – Red Cross Trail to Sheepfold: [Link to: Skyline2-RedCrossSheepfold-SelfGuide.pdf]
Skyline 3 –Sheepfold to Bear Hill: [Link to: Skyline3-SheepfoldBearHill-SelfGuide.pdf]
Skyline 4 –Bear Hill to Grinding Rock Hill: [Link to: Skyline4-BearHilltoGrindingRockHill-SelfGuide.pdf]
Skyline 5 – Grinding Rock Hill to Molly Spring: [Link to: Skyline5-GrindingRocktoMollySpring-SelfGuide.pdf]
Skyline 6 – Molly Spring to South Reservoir Outlet: [Link to: Skyline6-MollySpringtoSResOutlet-SelfGuide.pdf]
Skyline 7 – South Reservoir Outlet (South Border Road) to Bellevue Pond: [Link to: Skyline7-SResOutlettoBellevuePond-SelfGuide.pdf]
The Rock Circuit Trail – The geology of the southeastern Fells. The Rock Circuit Trail hike is in three segments that form a 5-6 mile (9-10 km) loop. The hikes are most informative, and easier to understand and follow, if they are done in order. Below you will also find a link for doing all three segments in one day. This is a lot for one hike, and I don’t recommend this! At the beginning of each hike is information about how to connect to the starting point of each hike, and in some cases alternate starting points and routes.
Here is a link to a short video I narrated for the Friends of the Fells on the Rock Circuit Trail. The video was filmed on Rock Circuit 3 below and discusses volcanic rocks: Rocking in the Middlesex Fells: The Rock Circuit Trail – YouTube
Rock Circuit 1 – Pinnacle Rock to Cross Fells Trail: [Link: Rock Circuit 1-Pinnacle Rock to Cross Fells Trail.pdf]
Rock Circuit 2 – Cross Fells Trail to Hemlock Pool: [Link: Rock Circuit 2-Cross Fells to Hemlock Pool.pdf]
Rock Circuit 3 – Hemlock Pool to Fellsway East: [Link: Rock Circuit 3-Hemlock Pool to Fellsway East.pdf]
Rock Circuit 1 to 3: Loop of all three segments: [Link: Rock Circuit 1 to 3.pdf]
The Crystal Spring and Virginia Woods Trails – The geology of the eastern and northeastern Fells. The Crystal Springs Trail hike takes you from Pond Street and north in a loop to Wamoset and Whip Hills and the Greenwood Park areas. The Virginia Wood Trail takes you south of pond Street through Virginia Wood and its historic trail and to south of Ravine Road. (Note: The Virginia Wood Trail is also marked as part of the Crystal Spring Trail in some places on DCR signs.) Each hike can easily be finished in part of a day (2-3 hours). At the beginning of each hike is information about how to connect to the starting point of each hike. NOTE: On previous versions of the guides the Westboro Formation was called the Virginia Wood Quartzite. The Virginia Wood is now known to be a part of the Westboro.
The Crystal Springs Trail – Pond Street and areas to the north: [Link: Crystal Spring 1-north of Pond Street.pdf]
The Virginia Wood Trail – Pond Street and areas to the south: [Link: Virginia Wood 2-south of Pond Street.pdf]
Lawrence Woods. New as of July 31, 2021. The Lawrence Woods self-guided hike takes you on a loop east of Medford High School from the Medford HS parking lot to close to South Border Road and back. This trip focuses on some of the large igneous rock units of the southwestern Fells and the rocks they intruded as well as much younger glacial features. This tour is meant as an educational hike and provides special explanations of how large bodies of granite (plutons) form and how igneous rocks are numerically dated. This hike has been used as a route I take Medford HS students on for Fells Day.
Lawrence Woods Loop: [Link: Lawrence Woods self guide.pdf]