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Roxbury Puddingstone
The Roxbury Conglomerate, also informally known as Roxbury puddingstone, is a name for a rock formation that forms the bedrock underlying most of Roxbury, Massachusetts, now part of the city of Boston. The bedrock formation extends well beyond the limits of Roxbury, underlying part or all of Quincy, Canton, Milton, Dorchester, Dedham, Jamaica Plain, Brighton, Brookline, Newton, Needham, and Dover. It is named for exposures in Roxbury, Boston area.Zen, E., R. Goldsmith, Richard N. M. Ratcliffe, P. Robinson, R. S. Stanley, N. L. Hatch Jr., A. F. Shride, E. G. A. Weed, and D. R. Jones (1983"Bedrock geologic map of Massachusetts".Special Map, 3 sheets, scale 1:125,000. U.S. Geological Survey, Reston, Virginia.Goldsmith, R. (1991In N. L. Hatch, ed., pp. E1–E62, Chapter E, "The bedrock geology of Massachusetts". Professional Paper. no. 1366-E. U.S. Geological Survey, Reston, Virginia. Description The Roxbury Conglomerate comprises the lower part of the Boston Bay Group, which is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gettysburg Battlefield
The Gettysburg Battlefield is the area of the July 1–3, 1863, military engagements of the Battle of Gettysburg within and around the borough of Gettysburg, Pennsylvania. Locations of military engagements extend from the site of the first shot & at Knoxlyn Ridge on the west of the borough, to East Cavalry Field on the east. A military engagement prior to the battle was conducted at the Gettysburg Railroad trestle over Rock Creek (Monocacy River tributary), Rock Creek, which was burned on June 27. Geography Within of the Mason-Dixon line, Maryland/Pennsylvania state line, the Gettysburg battlefield is situated in the Geology of Pennsylvania#Gettysburg-Newark Lowlands, Gettysburg-Newark Basin of the Pennsylvania Regions#Pennsylvania Piedmont, Pennsylvania Piedmont entirely within the Potomac River Watershed near the Marsh and Rock creeks' triple point with the Susquehanna River Watershed (near Oak Hill) occupying an area . Military engagements occurred within and around the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brighton, Massachusetts
Brighton is a Municipal annexation in the United States, former town and current Neighborhoods in Boston, neighborhood of Boston, Massachusetts, United States, located in the northwestern corner of the city. It is named after the English city of Brighton and Hove, Brighton. Initially Brighton was part of Cambridge, Massachusetts, Cambridge, and known as "Little Cambridge". Brighton separated from Cambridge in 1807 after a bridge dispute, and was annexed to Boston in 1874. For much of its early history, it was a rural town with a significant commercial center at its eastern end. The neighborhood of Allston was also formerly part of the town of Brighton, but is now often considered to be separate, leading to the name Allston–Brighton for the combined area. This historic center of Brighton is the Brighton Center Historic District. The Aberdeen section of Brighton was designated as a local architectural conservation district by the Boston Landmarks Commission in 2001. History In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, W. H. Freeman, 2nd ed, 529 pp. The term ''mudstone'' is also used to describe carbonate rocks (limestone or dolomite) that are composed predominantly of carbonate mud. However, in most contexts, the term refers to siliciclastic mudstone, composed mostly of silicate minerals. The NASA Curiosity rover has found deposits of mudstone on Mars that contain organic substances such as propane, benzene and toluene. Definition There is not a single definition of mudstone that has gained general acceptance,Boggs 2006, p.143 though there is wide agreement that mudstones are fine-grained sedimentary rocks, composed mostly of silicate grains with a grain size less than . Individual grains this size are too small to be disting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, pp.381-382 Although its permeability and porosity is relatively low, siltstone is sometimes a tight gas reservoir rock, an unconventional reservoir for natural gas that requires hydraulic fracturing for economic gas production. Siltstone was prized in ancient Egypt for manufacturing statuary and cosmetic palettes. The siltstone quarried at Wadi Hammamat was a hard, fine-grained siltstone that resisted flaking and was almost ideal for such uses. Description There is not complete agreement on the definition of siltstone. One definition is that siltstone is mudrock ( clastic sedimentary rock containing at least 50% clay and silt) in which at least 2/3 of the clay and silt fraction is composed of silt-sized particles. Silt is defined a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartz Monzonite
Quartz monzonite is an intrusive, felsic, igneous rock that has an approximately equal proportion of orthoclase and plagioclase feldspars. It is typically a light colored phaneritic (coarse-grained) to porphyritic granitic rock. The plagioclase is typically intermediate to sodic in composition, andesine to oligoclase. Quartz is present in significant amounts. Biotite and/or hornblende constitute the dark minerals. Because of its coloring, it is often confused with granite, but whereas granite contains more than 20% quartz, quartz monzonite is only 5–20% quartz. Rock with less than five percent quartz is classified as monzonite. A rock with more alkali feldspar is a syenite whereas one with more plagioclase is a quartz diorite.Classification of Igneous Rocks The fine grained |
Granite
Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous intrusions. These range in size from dikes only a few centimeters across to batholiths exposed over hundreds of square kilometers. Granite is typical of a larger family of ''granitic rocks'', or ''granitoids'', that are composed mostly of coarse-grained quartz and feldspars in varying proportions. These rocks are classified by the relative percentages of quartz, alkali feldspar, and plagioclase (the QAPF classification), with true granite representing granitic rocks rich in quartz and alkali feldspar. Most granitic rocks also contain mica or amphibole minerals, though a few (known as leucogranites) contain almost no dark minerals. Granite is nearly alway ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartzite
Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of hematite. Other colors, such as yellow, green, blue and orange, are due to other minerals. The term ''quartzite'' is also sometimes used for very hard but unmetamorphosed sandstones that are composed of quartz grains thoroughly cemented with additional quartz. Such sedimentary rock has come to be described as orthoquartzite to distinguish it from metamorphic quartzite, which is sometimes called metaquartzite to emphasize its metamorphic origins. Quartzite is very resistant to chemical weathering and often forms ridges and resistant hilltops. The nearly pure silica conte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobble (geology)
A cobble (sometimes a cobblestone) is a clast of rock defined on the Udden–Wentworth scale as having a particle size of , larger than a pebble and smaller than a boulder. Other scales define a cobble's size differently. A rock made predominantly of cobbles is termed a conglomerate. Cobblestone is a building material based on cobbles. Etymology Cobbles, also called cobblestones, derive their name from the word cob, meaning a rounded lump. The term is further related to the German ', meaning ''head''. Chester Wentworth referred to cobbles as ''cobble bowlders'' in his 1922 paper that would become the basis for the Udden–Wentworth scale. Classifications Within the widely used Krumbein phi scale of grain sizes, cobbles are defined as clasts of rock ranging from −6 to −8 φ. This classification corresponds with the Udden–Wentworth size scale which defines cobbles as clasts with diameters from . On this scale, cobbles are larger than pebbles which measure in diameter a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pebble
A pebble is a clast of rock with a particle size of based on the Udden-Wentworth scale of sedimentology. Pebbles are generally considered larger than granules ( in diameter) and smaller than cobbles ( in diameter). A rock made predominantly of pebbles is termed a conglomerate. Pebble tools are among the earliest known man-made artifacts, dating from the Palaeolithic period of human history. A beach composed chiefly of surface pebbles is commonly termed a shingle beach. This type of beach has armoring characteristics with respect to wave erosion, as well as ecological niches that provide habitat for animals and plants. Inshore banks of shingle (large quantities of pebbles) exist in some locations, such as the entrance to the River Ore, England, where the moving banks of shingle give notable navigational challenges. Pebbles come in various colors and textures and can have streaks, known as veins, of quartz or other minerals. Pebbles are mostly smooth but, dependent on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Puddingstone (rock)
Puddingstone, also known as either pudding stone or plum-pudding stone, is a popular name applied to a conglomerate that consists of distinctly rounded pebbles whose colours contrast sharply with the colour of the finer-grained, often sandy, matrix or cement surrounding them. The rounded pebbles and the sharp contrast in colour gives this type of conglomerate the appearance of a raisin or Christmas pudding.Neuendorf, K.E.K., J.P. Mehl, Jr., and J.A. Jackson (2005) ''Glossary of Geology.'' Springer-Verlag, New York, 779 pp., The McGraw-Hill Companies (2003) ''McGraw-Hill dictionary of geology and mineralogy'', 2nd ed. The McGraw-Hill Companies, Inc, New York, 420 pp., There are different types of puddingstone, with different composition, origin, and geographical distribution. Examples of different types of puddingstones include the Hertfordshire, Schunemunk, Roxbury, and St. Joseph Island (Drummond Island) puddingstones. Hertfordshire puddingstone Hertfordshire puddingstone is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoproterozoic
The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is preceded by the Mesoproterozoic Era and succeeded by the Paleozoic Era of the Phanerozoic Eon. The most severe glaciation known in the geologic record occurred during the Cryogenian, when ice sheets may have reached the equator and formed a " Snowball Earth". The earliest fossils of complex multicellular life are found in the Ediacaran Period. These organisms make up the Ediacaran biota, including the oldest definitive animals in the fossil record. According to Rino and co-workers, the sum of the continental crust formed in the Pan-African orogeny and the Grenville orogeny makes the Neoproterozoic the period of Earth's history that has produced most continental crust. Geology At the onset of the Neoproterozoic the supercontine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dover, Massachusetts
Dover is a town in Norfolk County, Massachusetts, United States. The population was 5,923 at the time of the 2020 United States Census. With a median income of more than $250,000, Dover is one of the wealthiest towns in Massachusetts. Located about southwest of downtown Boston, Dover is a residential town nestled on the south banks of the Charles River. Almost all of the residential zoning requires or larger. As recently as the early 1960s, 75% of its annual town budget was allocated to snow removal, as only a mile and a half of the town's roads are state highway. Dover is bordered by Natick, Wellesley and Needham to the north, Westwood to the east, Walpole and Medfield to the south, and Sherborn to the west. For geographic and demographic information on the census-designated place Dover, please see the article Dover (CDP), Massachusetts. The "Dover Demon" is a creature reportedly sighted on April 21 and April 22, 1977. History The first recorded settlement of Dover ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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