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The Marcy Group, or Marcy Massif is a subset of the Great Range of the Adirondack Mountains, near Keene Valley, New York, United States. It consists of the High Peaks near Mount Marcy [1] at the southern end of the Great Range, Allen Mountain, Cliff Mountain, Mount Colden, Gray Peak, Mount Haystack, Mount Redfield, and Mount Skylight, and the lesser peaks McDonnel Mountain, North River Mountains Peak, and Rist Mountain.
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The group is unique for its formation and composition of minerals, [2] particularly for its composition of anorthosite rock. [3] The Marcy massif includes two separate groups of plutons, an eastern and western range. The western range is situated near the St. Regis [4] and Long Lake quadrangles [5] and the eastern Marcy group is sited near Jay, Hurricane Mountain, and the town of North Hudson. [6]
Orogeny is a mountain-building process that takes place at a convergent plate margin when plate motion compresses the margin. An orogenic belt or orogen develops as the compressed plate crumples and is uplifted to form one or more mountain ranges. This involves a series of geological processes collectively called orogenesis. These include both structural deformation of existing continental crust and the creation of new continental crust through volcanism. Magma rising in the orogen carries less dense material upwards while leaving more dense material behind, resulting in compositional differentiation of Earth's lithosphere. A synorogenic process or event is one that occurs during an orogeny.
The Adirondack Mountains are a massif of mountains in Northeastern New York which form a circular dome approximately 160 miles (260 km) wide and covering about 5,000 square miles (13,000 km2). The region contains more than 100 peaks, including Mount Marcy, which is the highest point in New York at 5,344 feet (1,629 m). The Adirondack High Peaks, a traditional list of 46 peaks over 4,000 feet (1,200 m), are popular hiking destinations. There are over 200 named lakes with the number of smaller lakes, ponds, and other bodies of water reaching over 3,000. Among the named lakes around the mountains are Lake George, Lake Placid, and Lake Tear of the Clouds. The region has over 1,200 miles (1,900 km) of river.
A massif is a principal mountain mass, such as a compact portion of a mountain range, containing one or more summits. In mountaineering literature, a massif is frequently used to denote the main mass of an individual mountain.
Anorthosite is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most commonly present.
Mount Marcy is the highest point in the U.S. state of New York, with an elevation of 5,343.1 feet (1,628.6 m). It is located in the town of Keene in Essex County. The mountain is in the heart of the High Peaks Wilderness Area in Adirondack Park. Like the surrounding Adirondack Mountains, Marcy was heavily affected by large glaciers during recent ice ages, which deposited boulders on the mountain slopes and carved valleys and depressions on the mountain. One such depression is today filled by Lake Tear of the Clouds, which is often cited as the highest source of the Hudson River. The majority of the mountain is covered by hardwood and spruce-fir forests, although the highest few hundred feet are above the tree line. The peak is dominated by rocky outcrops, lichens, and alpine plants. The mountain supports a diverse number of woodland mammals and birds.
The Antler orogeny was a tectonic event that began in the early Late Devonian with widespread effects continuing into the Mississippian and early Pennsylvanian. Most of the evidence for this event is in Nevada but the limits of its reach are unknown. A great volume of conglomeratic deposits of mainly Mississippian age in Nevada and adjacent areas testifies to the existence of an important tectonic event, and implies nearby areas of uplift and erosion, but the nature and cause of that event are uncertain and in dispute. Although it is known as an orogeny, some of the classic features of orogeny as commonly defined such as metamorphism, and granitic intrusives have not been linked to it. In spite of this, the event is universally designated as an orogeny and that practice is continued here. This article outlines what is known and unknown about the Antler orogeny and describes three current theories regarding its nature and origin.
In geology, continental collision is a phenomenon of plate tectonics that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together. Continental collision is only known to occur on Earth.
The Nevadan orogeny occurred along the western margin of North America during the Late Jurassic to Early Cretaceous approximately 155 Ma to 145 Ma. Throughout the duration of this orogeny there were at least two different kinds of orogenic processes occurring. During the early stages of orogenesis an "Andean type" continental magmatic arc developed due to subduction of the Farallon oceanic plate beneath the North American Plate. The latter stages of orogenesis, in contrast, saw multiple oceanic arc terranes accreted onto the western margin of North America in a "Cordilleran type" accretionary orogen. Deformation related to the accretion of these volcanic arc terranes is mostly limited to the western regions of the resulting mountain ranges and is absent from the eastern regions. In addition, the deformation experienced in these mountain ranges is mostly due to the Nevadan orogeny and not other external events such as the more recent Sevier and Laramide Orogenies. It is noted that the Klamath Mountains and the Sierra Nevada share similar stratigraphy indicating that they were both formed by the Nevadan orogeny. In comparison with other orogenic events, it appears that the Nevadan Orogeny occurred rather quickly taking only about 10 million years as compared to hundreds of millions of years for other orogenies around the world.
The Grenville orogeny was a long-lived Mesoproterozoic mountain-building event associated with the assembly of the supercontinent Rodinia. Its record is a prominent orogenic belt which spans a significant portion of the North American continent, from Labrador to Mexico, as well as to Scotland.
Burrell Clark Burchfiel was an American structural geologist. Born in Stockton, California, he earned his Ph.D. in 1961 at Yale University. His first academic appointment was to the Geology department at Rice University. He was the Schlumberger Professor Emeritus of Geology at MIT. Research interests: Origin, development, and structural evolution of the continental crust. His later work involved study of the geological history and evolution of the Tibetan plateau.
Mount Emmons is a mountain located in the Adirondack Mountains near the southern edge of Franklin County, New York, United States.
The MacIntyre Mountains or MacIntyre Range is a range of mountains in the High Peaks region of the Adirondacks, due west of Mount Marcy, in northeastern New York State. The range runs 8 miles (13 km) from southwest to northeast. Its sheer southwest slope makes up one side of Indian Pass, and a northeastern spur forms the cliffs of Avalanche Pass. From southwest to northeast, the range includes Mount Marshall, Iroquois Peak, Boundary Peak, Algonquin Peak, and Wright Peak. Algonquin is the second-highest peak in the Adirondacks.
The East Antarctic Shield or Craton is a cratonic rock body that covers 10.2 million square kilometers or roughly 73% of the continent of Antarctica. The shield is almost entirely buried by the East Antarctic Ice Sheet that has an average thickness of 2200 meters but reaches up to 4700 meters in some locations. East Antarctica is separated from West Antarctica by the 100–300 kilometer wide Transantarctic Mountains, which span nearly 3,500 kilometers from the Weddell Sea to the Ross Sea. The East Antarctic Shield is then divided into an extensive central craton that occupies most of the continental interior and various other marginal cratons that are exposed along the coast.
Mount Luyendyk is a summit in the western Fosdick Mountains of the Ford Ranges of Marie Byrd Land, West Antarctica. It forms a prominent exposure in the northwestern Iphigene massif. The peak is named in recognition of Bruce P. Luyendyk, professor (emeritus), University of California, Santa Barbara, who was active in ground- and ocean-based Antarctic research from 1989 to 2015, significantly advancing the scientific knowledge of the Ross Embayment region of Antarctica. Luyendyk led two on-land expeditions in the Ford Ranges, and was principal investigator for five marine geophysical expeditions in the Ross Sea.
The Grenville Province is a tectonically complex region, in Eastern Canada, that contains many different aged accreted terranes from various origins. It exists southeast of the Grenville Front and extends from Labrador southwestern to Lake Huron. It is bounded by the St. Lawrence River/Seaway to the southeast.
The Mazatzal orogeny was an orogenic event in what is now the Southwestern United States from 1650 to 1600 Mya in the Statherian Period of the Paleoproterozoic. Preserved in the rocks of New Mexico and Arizona, it is interpreted as the collision of the 1700-1600 Mya age Mazatzal island arc terrane with the proto-North American continent. This was the second in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism.
The Yavapai orogeny was an orogenic (mountain-building) event in what is now the Southwestern United States that occurred between 1710 and 1680 million years ago (Mya), in the Statherian Period of the Paleoproterozoic. Recorded in the rocks of New Mexico and Arizona, it is interpreted as the collision of the 1800-1700 Mya age Yavapai island arc terrane with the proto-North American continent. This was the first in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism.
The Picuris orogeny was an orogenic event in what is now the Southwestern United States from 1.43 to 1.3 billion years ago in the Calymmian Period of the Mesoproterozoic. The event is named for the Picuris Mountains in northern New Mexico and interpreted either as the suturing of the Granite-Rhyolite crustal province to the southern margin of the proto-North American continent Laurentia or as the final suturing of the Mazatzal crustal province onto Laurentia. According to the former hypothesis, this was the second in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism.
Gore Mountain Garnet, found in the Adirondack Mountains in New York, contains the world's largest garnets. The rock that holds these garnets, garnet amphibolite, is sometimes referred to as 'black ore' or 'dark ore.' This rock formation formed during metamorphism during the Ottawan phase of the Grenvillian orogeny, and extremely high temperatures combined with introduction of fluids is what most likely contributed to the unusual size of the megacrystic garnets.
The Nevadaplano was a high plateau that is proposed to have covered parts of southwestern North America during the late Mesozoic and early Cenozoic, located in the present-day US states of Idaho, Nevada, Utah and possibly others. It most likely formed during the Cretaceous as a consequence of subduction dynamics and may have reached elevations of 3 kilometres (9,800 ft) and more, although its elevation is controversial. It was flanked on the west by the Sierra Nevada, which was traversed by various valleys that came down from the Nevadaplano. Closed basins and numerous volcanic calderas covered the relatively flat Nevadaplano; large volcanic eruptions distributed ignimbrites over the plateau and down the valleys draining it.
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