4. Glacial Terraces 9. Basalt ridge and south slope Parking The land along the trail alternates At the Summit House and most of the Self-guided There are several places to park for the between fairly level to quite sloping. other summits on the Range. geology walking tour at Skinner State Along the Devils’ Football Trail, 10. Glacial smoothing on basalt Park: Geology between the Devils Football boulder and At the summit, looking down the Halfway Rte. 47; along the Halfway House Trail Trail from the deck’s west staircase. • At the Skinner State Park between the Halfway Area and Rte. 47. Elsewhere, many places throughout the Main Gate parking area. Walking Tour 5. Conglomerate Rock Mt. Holyoke Range. • Along the unpaved section of From the Halfway Area, walk uphill 11. Glacial grooves on basalt Skinner Park Road (note that along the Auto Road to the red-blazed Can be difficult to see at times. Sometimes the road is one-way). Skinner State Park Conglomerate Rock Trail on your left. low-angled light makes them more visible. • At the Halfway Area parking lot. The boulder is about 200 yards along Near the summit picnic grove’s north end, Mt. Holyoke Range the trail. on sloping basalt bedrock. • At the Summit parking lot. State Park 6. Vesicular Basalt fragments To continue the tour, drive to the Mt. For the Mt. Holyoke Range State Park, These are small
” – 2” rocks lying on Holyoke Range Notch Visitors Center on park at the Visitors Center on Rte. 116. the ground. Further up the Auto Road Rte. 116. near Taylor’s Notch: as you walk toward the summit, they are at the base of a cliff 12. Basalt Talus Slope at Mt. Holyoke Maps across the road from the cement guard Range State Park rail. Also along Halfway Trail – just Southbound along the M-M trail from the Trail maps are available at the Summit before and at the sharp elbow bend. Notch Visitors Center, about a third of the House at Skinner State Park or at the Mt. Holyoke Range Notch Visitors Center. 7. Sedimentary rock cliff and way up Bare Mountain, is an impressive outcrops slope of brick-sized basalt fragments. They can also be downloaded from the Along the auto road near Taylor’s 13. Horse Caves at Mt. Holyoke DCR website at www.mass.gov/dcr Notch: as you walk toward the summit, Range State Park this cliff is across the road from the On the white-blazed Metacomet- cement guardrail. Also along Halfway Monadnock trail, about 250 yards north of Trail, both before and just after the sharp the Norwottuck summit. The caves can be elbow bend. reached by a variety of trails. The shortest SKINNER STATE PARK 8. Basalt / Sedimentary Rock route is the MM trail northbound via Mountain Road, Hadley contact zone Norwottuck summit, with steep pitches 413-586-0350 Conglomerate Rock in Skinner State Park The sedimentary outcrop ends suddenly, and loose rocky footing in places. The MT. HOLYOKE RANGE STATE PARK replaced by blocks of basalt. orange-blazed Robert Frost trail to the Rte. 116, Amherst Along the Auto Road, just at Taylor’s white-blazed M-M trail southbound is a 413 586-0350 Notch, look up the cliff. longer but easier route on old woods roads Department of Conservation and Recreation with rolling hills. www.mass.gov/dcr Columnar basalt occurs when lava cools more Begin the Tour! Connecticut River slowly, allowing its fracturing pattern to Valley geohistory gradually develop. Titan’s Piazza at Skinner Be sure to pick up a trail map before State Park is a stunning example. The lower you set off. Most sources agree that the landscape of edges of its polygonal columns are in present-day Massachusetts originated with scalloping folds, giving it the look of a 1. Titan’s Piazza the accretion of many smaller colliding land massive theater curtain. Park at the Main Gate on Mountain masses of the supercontinent Pangea, Road and walk about 300 yards down roughly 450 to 250 million years ago. Small, inch-size stones with tiny holes are fragments of vesicular basalt. This is the the unpaved section of Skinner Park Then, around 220 million years ago, Pangea result of lava hardening soon after reaching Road. A short trail on the left leads up began to rift apart. This created a lowland the surface. It is occasionally seen where the to a clearing where this magnificent basin, edged by towering 4,000 foot basalt makes contact with sedimentary rock or formation is more easily seen. Please highlands, the ancestor of today’s on south-facing slopes. avoid walking up the steep slope with Connecticut River Valley. Over time, the The basalt layer forming the Mt. Holyoke slippery loose basalt fragments to Range is tilted upwards. The Ice Age left its mark on many of the highlands eroded, washed into the basin and Titan’s Piazza base. ultimately hardened into sedimentary rock. land’s surface features. The glacier spread Over time this rock eroded away, leaving southward, scooping up everything in its path. The grain size and shape of the rock 2. Quartzite boulders behind the roof and walls of the more Within the glacier, some rocks disintegrated particles indicates how fast the waters Tan to white in color, some rounded strongly-cemented conglomerate. back into sediments – sand, silt and clay. flowed when they deposited their sediments. Others fractured into gravel, pebbles, cobbles smooth, others more angular and Larger fragments settled to the bottom of As the highlands wore down, lava oozed from and boulders of various sizes. When the revealing the quartz minerals fused swiftly-flowing streams. The smoother and vents deep within the earth. It flooded the climate warmed, torrents of meltwater formed together. Return to the Main Gate and smaller the fragments, the farther they basin and hardened into a rock called basalt. enormous rivers. Filled with rocks and walk uphill along the Auto Road. The traveled, tumbling and rounding out their When the earth’s crust shifted and moved, the sediments, they tumbled down the barren hills. boulders are scattered along the road edges. Very tiny grains means the sediments basalt sheet tilted upwards. What was Their waters filled glacial Lake Hitchcock, between the Main Gate and Taylor’s originally flat is now upended, hundreds of washed into the still-water environment of which covered much of the valley floor. Notch. shallow “playa” lakes. feet higher than the valley floor. We see evidence of glacial action throughout Skinner State Park’s Conglomerate Rock is As it hardened, the basalt developed cracks the valley and on the Mt. Holyoke Range. 3. Devil’s Football filled with large fragments embedded into a and chunks of the basalt sheet broke off into Lawrence Swamp is a vestige of Lake Park at the Halfway Area and walk sandy matrix. This suggests it originally individual rocks. Their sharp angles reflect Hitchcock. Mount Castor and Pollux in downhill about 130 yards on the Auto formed near the edge of the highlands in this fracture pattern. The rock is heavy, dark South Amherst are drumlins. Sand dunes lie Road to the start of the yellow-blazed high-velocity streams. Some of the eroding and rich in the element iron. It can take on a near the ancient lake’s eastern shoreline. Two-Forest Trail on your right, sediments dropped smaller-grained particles reddish cast like rusted nails. opposite the Halfway Trail steps. The in slower-flowing or still-water environ- We occasionally find shallow, glacial grooves Devil’s Football, a basalt boulder near the trail leads directly to the Devil’s ments. They lithified, layer upon layer, and on the basalt rock on the Mt. Holyoke Range. Halfway Area at Skinner State Park, has all Football, at the intersection with the are now outcrops or cliffs, such as the cliff About as wide as a thumb, they run in long, these features including a few spots where a blue-blazed Devil’s Football Trail. near Taylor’s Notch at Skinner State Park. parallel rows. As the glacier melted, Lake compass needle pulls away from north and Hitchcock formed terraces, and some are The Horse Caves, overhanging ledges on points to the rock. visible along trails on Mount Holyoke’s Mt. Norwottuck, are mostly conglomerate. Enormous basalt columns, much thicker than northwest flank. The glacier also left Within are remains of fine-grained, thinly large tree trunks and much taller, are scattered quartzite boulders scattered throughout the layered sedimentary rock. throughout the park. range as it retreated north.