Mountain range in Connecticut and Massachusetts, United States
The Metacomet Ridge, Metacomet Ridge Mountains, or Metacomet Range of southern New England is a narrow and steep fault-block mountain ridge known for its extensive cliff faces, scenic vistas, microclimate ecosystems, and rare or endangered plants. The ridge is an important recreation resource located within of more than 1.5 million people, offering four long-distance hiking trails and over a dozen parks and recreation areas, including several historic sites. It has been the focus of ongoing conservation efforts because of its natural, historic, and recreational value, involving municipal, state, and national agencies and nearly two dozen non-profit organizations.
The Metacomet Ridge extends from Branford, Connecticut, on Long Island Sound, through the Connecticut River Valley region of Massachusetts, to northern Franklin County, Massachusetts, short of the Vermont and New Hampshire borders for a distance of . It is geologically distinct from the nearby Appalachian Mountains and surrounding uplands, and is composed of volcanic basalt (also known as "trap rock") and sedimentary rock in faulted and tilted layers many hundreds of feet thick. In most cases, the basalt layers are dominant, prevalent, and exposed. The ridge rises dramatically from much lower valley elevations, although only above sea level at its highest, with an average summit elevation of .
Geographic definitions.
Visually, the Metacomet Ridge exists as one continuous landscape feature from Long Island Sound at Branford, Connecticut, to the end of the Mount Holyoke Range in Belchertown, Massachusetts, a distance of , broken only by the river gorges of the Farmington River in northern Connecticut and the Westfield and Connecticut Rivers in Massachusetts. It was first identified in 1985 as a single geologic feature consisting of trap rock by the State Geological and Natural History Survey of Connecticut. A 2004 report conducted for the National Park Service extends that definition to include the entire traprock ridge from Long Island Sound to the Pocumtuck Range in Greenfield, Massachusetts. Further complicating the matter is the fact that traprock only accounts for the highest surface layers of rock strata on the southern three–fourths of the range; an underlying geology of related sedimentary rock is also a part of the structure of the ridge; in north central Massachusetts it becomes the dominant strata and extends the range geologically from the Holyoke Range another through Greenfield to nearly the Vermont border.
Nomenclature.
Until January 2008, the United States Board on Geographic Names (USBGN) did not recognize "Metacomet Ridge," "Traprock Ridge" or any other name, although several sub-ranges were identified. Geologists usually refer to the overall range generically as "the traprock ridge" or "the traprock mountains" or refer to it with regard to its prehistoric geologic significance in technical terms. The Sierra Club has referred to the entire range in Connecticut as "The Traprock Ridge". The name "Metacomet Ridge" was first applied in 1985 in a book published by the Connecticut State Geological Survey, adopting the name from the existing Metacomet Trail along a large portion of the range in central Connecticut.
The name "Metacomet" or "Metacom" is borrowed from the 17th century sachem of the Wampanoag Tribe of southern New England who led his people during King Philip's War in the mid–17th century. Metacomet was also known as King Philip by early New England colonists. A number of features associated with the Metacomet Ridge are named after the sachem, including the Metacomet Trail, the Metacomet-Monadnock Trail, King Philip's Cave, King Philip Mountain, and Sachem Head. According to legend, Metacomet orchestrated the burning of Simsbury, Connecticut, and watched the conflagration from Talcott Mountain near the cave now named after him. The names Metacomet and King Philip have been applied to at least sixteen landscape features and over seventy-five businesses, schools, and civic organizations throughout southern New England.
Geography.
Beginning at Long Island Sound, the Metacomet Ridge commences as two parallel ridges with related sub-ridges and outcrops in between; the latter include the high butte–like cliffs of East Rock and the isolated peak of Peter's Rock. The western ridgeline of the Metacomet Ridge begins in New Haven, Connecticut, as West Rock Ridge and continues as Sleeping Giant, Mount Sanford, Peck Mountain, and Prospect Ridge, for a distance of before diminishing into a series of low profile outcrops just short of Southington, Connecticut, west of the Hanging Hills in Meriden.
To the east, beginning on the rocky prominence of Beacon Hill, , in Branford, Connecticut, overlooking the East Haven River estuary, the Metacomet Ridge continues as a traprock ridge north to Mount Tom in Holyoke, Massachusetts; it then breaks east across the Connecticut River to form the Holyoke Range, which continues for before terminating in Belchertown, Massachusetts. Several scattered parallel ridges flank it; the most prominent of these are the hills of Rocky Hill, Connecticut, and the Barn Door Hills of Granby, Connecticut.
North of Mount Tom and the Holyoke Range, the apparent crest of the Metacomet Ridge is broken by a discontinuity in the once dominant traprock strata. Underlying sedimentary layers remain but lack the same profile. Between the Holyoke Range and the Pocumtuck Ridge, a stretch of , the Metacomet Ridge exists only as a series of mostly nondescript rises set among flat plains of sedimentary bedrock. Mount Warner, , in Hadley, Massachusetts, the only significant peak in the area, is a geologically unrelated metamorphic rock landform that extends west into the sedimentary strata.
The Metacomet Ridge picks up elevation again with the Pocumtuck Ridge, beginning on Sugarloaf Mountain and the parallel massif of Mount Toby, , the high point of the Metacomet Ridge geography. Both Sugarloaf Mountain and Mount Toby are composed of erosion-resistant sedimentary rock. North of Mount Sugarloaf, the Pocumtuck Ridge continues as alternating sedimentary and traprock dominated strata to Greenfield, Massachusetts. From Greenfield north to Northfield, Massachusetts short of the Vermont–New Hampshire–Massachusetts tri-border, the profile of the Metacomet Ridge diminishes into a series of nondescript hills and low, wooded mountain peaks composed of sedimentary rock with dwindling traprock outcrops.
In Connecticut, the high point of the Metacomet Ridge is West Peak of the Hanging Hills at ; in Massachusetts, the highest "traprock" peak is Mount Tom, , although Mount Toby, made of sedimentary rock, is higher. Visually, the Metacomet Ridge is narrowest at Provin Mountain and East Mountain in Massachusetts where it is less than 0.5 miles (1 km) wide; it is widest at Totoket Mountain, over . However, low parallel hills and related strata along much of the range often make the actual geologic breadth of the Metacomet Ridge wider than the more noticeable ridgeline crests, up to across in some areas. Significant river drainages of the Metacomet Ridge include the Connecticut River and tributaries (Falls River, Deerfield River, Westfield River, Farmington River, Coginchaug River); and, in southern Connecticut, the Quinnipiac River.
The Metacomet Ridge is surrounded by rural wooded, agricultural, and suburban landscapes, and is no more than from a number of urban hubs such as New Haven, Meriden, New Britain, Hartford, and Springfield. Small city centers abutting the ridge include Greenfield, Northampton, Amherst, Holyoke, West Hartford, Farmington, Wallingford, and Hamden.
Geology.
The Metacomet Ridge is the result of continental rifting processes that took place 200 million years ago during the Triassic and Jurassic periods. The basalt (also called traprock) crest of the Metacomet Ridge is the product of a series of massive lava flows hundreds of feet thick that welled up in faults created by the rifting apart of the North American continent from Eurasia and Africa. Essentially, the area now occupied by the Metacomet Ridge is a prehistoric rift valley which was once a branch of (or a parallel of) the major rift to the east that became the Atlantic Ocean.
Basalt is a dark colored extrusive volcanic rock. The weathering of iron-bearing minerals within it results in a rusty brown color when exposed to air and water, lending it a distinct reddish or purple–red hue. Basalt frequently breaks into octagonal and pentagonal columns, creating a unique "postpile" appearance. Extensive slopes made of fractured basalt talus are visible at the base of many of the cliffs along the Metacomet Ridge.
The basalt floods of lava that now form much of the Metacomet Ridge took place over a span of 20 million years. Erosion and deposition occurring between the eruptions deposited layers of sediment between the lava flows which eventually lithified into sedimentary rock layers within the basalt. The resulting "layer cake" of basalt and sedimentary rock eventually faulted and tilted upward (see fault-block). Subsequent erosion wore away many of the weaker sedimentary layers at a faster rate than the basalt layers, leaving the abruptly tilted edges of the basalt sheets exposed, creating the distinct linear ridge and dramatic cliff faces visible today on the western and northern sides of the ridge. Evidence of this layer-cake structure is visible on Mount Norwottuck of the Holyoke Range in Massachusetts. The summit of Norwottuck is made of basalt; directly beneath the summit are the Horse Caves, a deep overhang where the weaker sedimentary layer has worn away at a more rapid rate than the basalt layer above it. Mount Sugarloaf, Pocumtuck Ridge, and Mount Toby, also in Massachusetts, together present a larger "layer cake" example. The bottom layer is composed of "arkose sandstone," visible on Mount Sugarloaf. The middle layer is composed of "volcanic traprock," most visible on the Pocumtuck Ridge. The top layer is composed of a sedimentary conglomerate known as "Mount Toby Conglomerate." Faulting and earthquakes during the period of continental rifting tilted the layers diagonally; subsequent erosion and glacial activity exposed the tilted layers of sandstone, basalt, and conglomerate visible today as three distinct mountain masses. Although Mount Toby and Mount Sugarloaf are not composed of traprock, they are part of the Metacomet Ridge by virtue of their origin via the same rifting and uplift processes.
Of all the summits that make up the Metacomet Ridge, West Rock, in New Haven, Connecticut, bears special mention because it was not formed by the volcanic flooding that created most of the traprock ridges. Rather, it is the remains of an enormous volcanic dike through which the basalt lava floods found access to the surface.
While the traprock cliffs remain the most obvious evidence of the prehistoric "geologic" processes of the Metacomet Ridge, the sedimentary rock of the ridge and surrounding terrain has produced equally significant evidence of prehistoric life in the form of Triassic and Jurassic fossils; in particular, dinosaur tracks. At a state park in Rocky Hill, Connecticut, more than 2,000 well preserved early Jurassic prints have been excavated. Other sites in Holyoke and Greenfield have likewise produced significant finds.
Ecosystem.
 The Metacomet Ridge hosts a combination of microclimates unusual to the region. Dry, hot upper ridges support oak savannas, often dominated by chestnut oak and a variety of understory grasses and ferns. Eastern red-cedar, a dry-loving species, clings to the barren edges of cliffs. Backslope plant communities tend to be similar to the adjacent upland plateaus and nearby Appalachians, containing species common to the northern hardwood and oak-hickory forest ecosystem types. Eastern hemlock crowds narrow ravines, blocking sunlight and creating damp, cooler growing conditions with associated cooler climate plant species. Talus slopes are especially rich in nutrients and support a number of calcium-loving plants uncommon in the region. Miles of high cliffs make ideal raptor habitat, and the Metacomet Ridge is a seasonal raptor migration corridor. 
Because the topography of the ridge offers such varied terrain, many species reach the northern or southern limit of their range on the Metacomet Ridge; others are considered rare nationally or globally. Examples of rare species that live on the ridge include the prickly pear cactus, peregrine falcon, northern copperhead, showy lady's slipper, yellow corydalis, ram's–head lady's slipper, basil mountain mint, and devil's bit lily.
The Metacomet Ridge is also an important aquifer. It provides municipalities and towns with public drinking water; reservoirs are located on Talcott Mountain, Totoket Mountain, Saltonstall Mountain, Bradley Mountain, Ragged Mountain, and the Hanging Hills in Connecticut. Reservoirs that supply metropolitan Springfield, Massachusetts, are located on Provin Mountain and East Mountain.
History.
Pre-colonial era.
Native Americans occupied the river valleys surrounding the Metacomet Ridge for at least 10,000 years. Major tribal groups active in the area included the Quinnipiac, Niantic, Pequot, Pocomtuc, and Mohegan. Traprock was used to make tools and arrowheads. Natives hunted game, gathered plants and fruits, and fished in local bodies of water around the Metacomet Ridge. Tracts of woodland in the