The natural scenery of the Northeast and Mid-Atlantic reveals a dramatic geological history, shaped over centuries by glaciers and volcanoes. For the observant hiker, clues as small as a pebble or as large as a mountainside can teach us about the landscape and its formation. Look for those telltale signs—and enjoy the hiking—in these eight unique spots.
1. HORSE MOUNTAIN
Baxter State Park, Maine
Horse Mountain’s volcanic cliffs are part of the Traveler Rhyolite formation. An expansive sheet of ash filled the crater of an active volcano more than 400 million years ago, hardening into the erosion-resistant rock visible today. Softer soil has since washed away, leaving Horse Mountain’s cliffs exposed. A distinctive feature of Baxter State Park, the formation is named for its highest peak, Traveler Mountain. This hike begins off Route 159, past the Matagamon Gatehouse on the northeastern edge of Baxter. Follow Horse Mountain Trail as it climbs 1.4 miles to the summit. A spur trail to the east of the summit leads to a scenic overlook.
DISTANCE: 3 miles round trip
INFO: Baxter State Park; Maine Mountain Guide, 10th ed. (AMC BOOKS)
2. THE BASIN
Evans Notch, N.H.
This hike affords excellent views of a glacial cirque, a bowl-shaped ravine scooped out by a glacier. By way of Basin Trail from the Wild River Campground, follow Blue Brook for just over 1 mile then ascend to Basin Rim, where the valley, Basin Pond, and a series of impressive cliffs extend out from the overlook. Formed during the last ice age, this east-facing cirque showcases the shaping power of ice and snow, as the contours reveal the path the glacier once traveled. You can turn around at Basin Rim or descend to Basin Pond to extend your hike another 1.5 miles.
DISTANCE: 4.6 miles round trip
INFO: AMC’s Best Day Hikes in the White Mountains, 3rd ed. (AMC BOOKS); White Mountain Guide, 29th ed. (AMC BOOKS); White Mountain Guide Online
3. BARTHOLOMEW’S COBBLE RESERVATION
Approximately 500 million years ago, shifting continental plates pushed sedimentary layers of marble and quartzite to the surface in western Massachusetts. These cobble conglomerates comprise gravel and stone cemented by silt. Follow Eaton Trail from the visitor center to examine the hill-sized formations up close. The soils produced by this mix of rock has led to tremendous biodiversity in the surrounding forest. Turn onto Bailey Trail and then Spero Trail to reach the banks of the Housatonic River, where you can see how the water has cut through the soft layers of marble and quartzite. Head west toward Hulbert’s Hill to enjoy its view of Mount Everett and the southern Taconic Mountains. Finally, take Woods Road to complete the loop.
DISTANCE: 3.2-mile loop
INFO: AMC’s Best Day Hikes in the Berkshires, 2nd ed. (AMC BOOKS); The Trustees
4. EAST MCLEAN GAME REFUGE
Millions of years ago, shifting continents forced molten rock through fissures in Earth’s crust. One string of ridges that arose in north-central Connecticut is now called the Barn Door Hills. A hike through East McLean offers an up-close look at how this igneous basaltic traprock shrank and cracked into hexagonal columns as it cooled. Look for jumbled, red-brown basalt in the woods past Trout Pond and distinctive geometric cliffs as you climb Stony Hill and East Barn Door Hill. Trails are unnamed, but maps are available in the parking lot.
DISTANCE: 3.5-mile loop
INFO: AMC’s Best Day Hikes in Connecticut (AMC BOOKS); Mclean Game Refuge
5. MILLBROOK MOUNTAIN
New Paltz, N.Y.
The Wisconsin Ice Sheet sliced Millbrook Mountain in half 100,000 years ago. Today the view from its cliffs looks down to the crumbled remains of the mountain’s other half, lying in the valley below. Park at the West Trapps lot and cross the bridge to Millbrook Ridge Trail. You’ll pass over Gertrude’s Nose, a long plateau of white conglomerate cap rock native to the Shawangunks region. Deep fractures in the plateau reach far into the cliffs, forming narrow crevasses, so proceed with caution—especially if there’s snow on the ground. Complete the loop by way of Coxing Trail and Trapps Road.
DISTANCE: 9.5-mile loop
INFO: AMC’s Best Day Hikes in the Catskills and Hudson Valley, 3rd ed. (AMC BOOKS); Mohonk Preserve
6. TURKEY MOUNTAIN NATURE PRESERVE
This short hike delivers some of the best views of the Palisades from the summit of Turkey Mountain. Begin the loop on the blue-blazed trail from the Turkey Mountain Nature Preserve parking lot. Wind your way up to the summit and an open grassy area that provides sweeping views of Croton Reservoir, High Tor, and Hook Mountain across the Hudson River and Bear Mountain beyond it. The Palisades are composed of diabase, a volcanic rock that squeezed through cracks in sedimentary layers 200 million years ago. They have resisted erosion and now rise 300 to 540 feet above the Hudson. From the summit, follow the white blazes, then green, then white again to return to the parking area.
DISTANCE: 1.8-mile loop
INFO: AMC’s Best Day Hikes Near New York City (AMC BOOKS); Yorktown Land Trust
7. NOLDE FOREST ENVIRONMENTAL EDUCATION CENTER
Pennsylvania’s first environmental education center, this 665-acre property contains portions of a formation created around the same time as the Palisades. Beneath thick forest, the red shale and sandstone common to this area is interrupted by sharp outcroppings of diabase. Pushed up under the sandstone and shale, this dark gray stone was eventually exposed as softer soils eroded around it. The effect is sudden jumbles of bare rock scattered throughout the thick undergrowth of the forest. Follow Boulevard Trail to see the most prominent of these diabase outcrops rising 15 feet in the air.
DISTANCE: 8-mile loop
INFO: AMC’s Best Day Hikes Near Philadelphia (AMC BOOKS); Nolde Forest Environmental Education Center
8. POTOMAC GORGE
Potomac Gorge features a series of dramatic waterfalls and rapids carved by the Potomac River over this area’s metamorphic bedrock. Today the river channel is 40 to 75 feet below the lip of the gorge, but this erosion took place over millions of years. Visitors will see the carving force of the water in the smooth rock underfoot and in the round boulders along the ancient riverbed. From within the Chesapeake & Ohio Canal National Historical Park, on the Maryland side of the river, take Gold Mine Loop, Valley Trail, and Billy Goat Trail into and out of the gorge by way of sloping cliffs and jumbled boulders. This hike features wide-ranging terrain, so be prepared for some rock scrambling.
DISTANCE: 8.2-mile loop
INFO: AMC’S Best Day Hikes Near Washington, D.C., 2nd ed. (AMC BOOKS); National Park Service
Robert Buchsbaum, Daniel Case, Susan Charkes, Mike Dickerman, Beth Homicz, Peter W. Kick, Carey M. Kish, René Laubach, Stephen Mauro, Charles W.G. Smith, Steven D. Smith