Purgatory Chasm


Useful Information

Location: Purgatory Chasm State Reservation.
(42.129040, -71.714988)
Open: Chasm Trail: APR to NOV daily sunrise to sunset.
[2020]
Fee: Park: free.
Parking: MA-Resident USD 5, Non-MA-Resident USD 20.
[2020]
Classification: GorgeGorge
Light: n/a
Dimension: L=400m, VR=21m
Guided tours: self guided
Photography: allowed
Accessibility: no
Bibliography: Steve Ulfelder (2012): Purgatory Chasm, Conway Sax Mystery, Griffin; Reprint Edition (24. April 2012). ISBN-10 : 9781250007025, ISBN-13 : 978-1250007025
Address: Purgatory Chasm State Reservation, 198 Purgatory Rd. , Sutton, MA 01590, Tel: +1-508-234-3733. E-mail:
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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History

1919 declared a state park.

Description

Purgatory Chasm is a gorge in granite located off Route 146 in the town of Sutton. The area is protected by the Purgatory Chasm State Reservation, is a state-owned geologic preserve and public recreation area. The state park has various trails, but the important one is obviously the Chasm Trail, which goes right through the gorge. In winter it might be difficult to walk because it could be slippery or icy, so it is closed.

The gorge, which is called chasm for unknown reasons, is 400m long and 21m deep. It is not clear how it was formed, it is definitely not due to erosion. There are several theories, the most likely is probably that the chasm was created when glacial meltwater from a burst ice dam ripped out blocks of bedrock at the end of the last Ice Age (14,000 years ago). The chasm or rift theory is also possible, though not undisputed. It would mean extensional tectonics which caused a central linear downfaulted depression called a graben. Unfortunately the Appalachians are a zone of orogeny and as such convergent.

Whatever the reasons, the forms inside the gorge are generally tectonic. There are huge granite blocks and numerous small caves created by the movement of the rock which created empty spaces or ledges inbetween. The most impressive cave is named His Majesty's Cave. Other rock formations are The Corn Crib, The Coffin and Lovers’ Leap.