The Holyoke Range or Mount Holyoke Range is a traprock mountain range located in the Connecticut River Valley of Massachusetts. It is a sub-range of the narrow, linear Metacomet Ridge that extends from Long Island Sound near New Haven, Connecticut north through the Connecticut River Valley of Massachusetts to the Vermont border. A popular hiking destination, the range is known for its anomalous east–west orientation, high ledges and its scenic character. It is also notable for its unique microclimate ecosystems and rare plant communities, as well as significant historic sites, such as the Mount Holyoke Summit House and the Horse Caves. Holyoke Range vs. Mount Holyoke Range Both names for the range are frequently cited by reputable published sources. For instance, both the Massachusetts Department of Conservation and Recreation and the non-profit Friends of the Mount Holyoke Range use Mount Holyoke Range, while the other form, Holyoke Range is used in several different map and guide sources (the USGS 1990 Belchertown 1:25000 scale topographic map, two longstanding popular retail hiking maps published by Newall Printing, the 1999 version of the Appalachian Mountain Club (AMC)'s Metacomet-Monadnock Trail Guide, and the 1989 version of the AMC's Massachusetts and Rhode Island Trail Guide). However, the AMC's 2004 Massachusetts Trail Guide uses "Mt. Holyoke Range" and the United States Board on Geographic Names now uses "Mount Holyoke Range".) Both names as well as the abbreviated Mt. Holyoke Range are used locally. Geography The Holyoke Range, located within the towns of South Hadley, Hadley, Granby, Amherst, and Belchertown, rises steeply between and above the Connecticut River Valley below; it has an east–west orientation and is roughly long by wide at its widest point, although the steepness of the terrain makes the actual square mileage much larger. The high point of range is the summit of Mount Norwottuck, above sea level. Notable peaks include, (from west to east) Mount Holyoke ; the Seven Sisters, a series of ridgeline knobs with a high point of ; Mount Hitchcock ; Bare Mountain ; Mount Norwottuck ; Rattlesnake Knob ; Long Mountain ; and Harris Hill . Round Mountain between Bare and Norwottuck has been removed by quarrying. A series of smaller, unnamed traprock hills continue from Long Mountain to the eastern end of the range. Another series of hills descends north from the range into the towns of Hadley and Amherst. Some of these have names: Tinker Hill