Beaver Brook Valley Preserve and Pettingell Park are located on the northwest side of the intersection of MA-111 and I-495. Follow Swanson Road to the end, turn right on Whitcomb Road, and park on the cul-de-sac. Follow the fenced corridor into the Beaver Brook Valley Preserve.

The 82 acres of Beaver Brook Valley Preserve contain a spectacular esker, many marshes, red maple swamps, hemlock, oak, hickory, and white pine forests. Beaver Brook parallels the esker on the west, and Muddy Pond is on the east. Nearby Pettingell Park contains 11 acres but is not currently accessible because of high water levels. Pettingell Park has no marked trails at this time.

Beaver Brook Valley Preserve is owned by the Boxborough Conservation Trust (BCTrust), and a conservation restriction on the property is held by The Nature Conservancy. Specific use guidelines for the property can be found here: https://bctrust.org/bctrust-property-trail-use-guidelines-4/. A well-marked trail that is over 2.5 miles long runs along a 65-foot-high esker (Boxborough Esker, also known as Ridge Hill). It is the third-longest and one of the best-preserved eskers in New England. Eskers form when a stream flows beneath a glacier and this one was deposited by one of the glaciers that covered much of New England during the last Ice Age. As the glacier melted and receded north, the stream underneath deposited sand and boulders. This sediment remained even after the ice completely melted, providing the dramatic ridge that we can walk on today. The trail is very steep in some sections, and the fenced entrance has high vegetation along the edges and can be very wet, laden with ticks and poison ivy.

In July 2006, Boxborough Conservation Trust acquired the Beaver Brook Valley Preserve, receiving ownership and stewardship of this property from The Nature Conservancy, which had acquired the property for conservation through five separate land transactions between 1965 and 1975. Boxborough resident John Pettingell gave Pettingell Park to the town in 1963 as conservation land.

The AllTrails website has a description and map of a hike at Beaver Brook Valley.