Naromi Land Trust and Great Hollow Nature Preserve will offer a guided hike at two small preserves near Dover Plains, N.Y., on Saturday.

Naturalist John Foley will lead the group.

Participants should meet at 9 a.m. at the Dover Elementary School parking lot, on Main Street (Route 22), across from the firehouse at the south end of Dover Plains).

Participants should wear sturdy shoes and bring water and a snack.

The group will walk along a naturally formed steep ravine that ends at an extraordinary cave-like formation shaped like a gothic arch, also known as Dover Stone Church.

A 30-foot waterfall cascades from above the ravine into this unusual open rock formation.

The easy walk to that point is about 25 minutes and traverses an open field, passes a large pond and then gradually goes uphill along the stream as the ravine sides grow steeper.

The group will retrace its steps back to the parking lot.

The group will then carpool to the Roger Perry Preserve of the Nature Conservancy, just a short drive east from the center of Dover Plains.

The hike will traverse over a trail of pure white sand leading through a red cedar forest, once known locally as the White Sands of Dover.

The site features a series of eroded limestone ridges and stunning bedrock outcrops.

Calcium-enriched ground water seeps through rivulets, creating an area of rich calcareous wetland fens. Fens support a unique assemblage of plant and wildlife, many of which are rare and endangered.

These two areas are suitable for children and adults. Dogs are not permitted.

For information and to register, call 860-354-0260 or email office@naromi.org.