Misplaced Pages

#796203

75-546: The soil and rocks of the range are of volcanic origin, composed mainly of rhyolite , which gives the hills a red color. The terrain is rugged, with deep ravines and oak forests. The highest point of the massif is Mont Vinaigre (618 metres or 2,028 feet). The massif covers an area of 320 km (123.5 sqmi), of which 130 km (50.1 sqmi) are protected by the Forêt domaniale de l'Esterel ( national forest ). The nature reserve offers hiking and mountain biking trails including

150-801: A free citizen ? Can a superpower still be a republic ? How does well-meaning authority turn into murderous tyranny ? Major sources for Roman myth include the Aeneid of Virgil and the first few books of Livy 's history as well as Dionysius's Roman Antiquities . Other important sources are the Fasti of Ovid , a six-book poem structured by the Roman religious calendar , and the fourth book of elegies by Propertius . Scenes from Roman myth also appear in Roman wall painting , coins , and sculpture , particularly reliefs . The Aeneid and Livy's early history are

225-519: A ghost town ) and Fourpeaked Mountain in Alaska, which, before its September 2006 eruption, had not erupted since before 8000 BCE. Roman mythology Roman mythology is the body of myths of ancient Rome as represented in the literature and visual arts of the Romans , and is a form of Roman folklore . "Roman mythology" may also refer to the modern study of these representations, and to

300-886: A mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift , the Wells Gray-Clearwater volcanic field , and the Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from

375-437: A graduated spectrum, with much overlap between categories, and does not always fit neatly into only one of these three separate categories. The USGS defines a volcano as "erupting" whenever the ejection of magma from any point on the volcano is visible, including visible magma still contained within the walls of the summit crater. While there is no international consensus among volcanologists on how to define an active volcano,

450-456: A mortal woman, the infant Hercules , on Juno 's breast while she is asleep so the baby will drink her divine milk and thus become immortal, an act which would endow the baby with godlike qualities. When Juno woke and realized that she was breastfeeding an unknown infant, she pushed him away, some of her milk spills, and the spurting milk became the Milky Way . In another version of the myth,

525-469: A native mythology. This perception is a product of Romanticism and the classical scholarship of the 19th century, which valued Greek civilization as more "authentically creative." From the Renaissance to the 18th century, however, Roman myths were an inspiration particularly for European painting . The Roman tradition is rich in historical myths, or legends , concerning the foundation and rise of

600-443: A paper was published suggesting a new definition for the word 'volcano' that includes processes such as cryovolcanism . It suggested that a volcano be defined as 'an opening on a planet or moon's surface from which magma , as defined for that body, and/or magmatic gas is erupted.' This article mainly covers volcanoes on Earth. See § Volcanoes on other celestial bodies and cryovolcano for more information. The word volcano

675-632: A volcano is largely determined by the composition of the lava it erupts. The viscosity (how fluid the lava is) and the amount of dissolved gas are the most important characteristics of magma, and both are largely determined by the amount of silica in the magma. Magma rich in silica is much more viscous than silica-poor magma, and silica-rich magma also tends to contain more dissolved gases. Lava can be broadly classified into four different compositions: Mafic lava flows show two varieties of surface texture: ʻAʻa (pronounced [ˈʔaʔa] ) and pāhoehoe ( [paːˈho.eˈho.e] ), both Hawaiian words. ʻAʻa

750-555: A volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are varied. The structure and behaviour of volcanoes depend on several factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus . Vents that issue volcanic material (including lava and ash ) and gases (mainly steam and magmatic gases) can develop anywhere on

825-465: A volcano that has experienced one or more eruptions that produced over 1,000 cubic kilometres (240 cu mi) of volcanic deposits in a single explosive event. Such eruptions occur when a very large magma chamber full of gas-rich, silicic magma is emptied in a catastrophic caldera -forming eruption. Ash flow tuffs emplaced by such eruptions are the only volcanic product with volumes rivalling those of flood basalts . Supervolcano eruptions, while

SECTION 10

#1732773307797

900-739: Is a volcanic field of over 60 cinder cones. Based on satellite images, it has been suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and the Moon. Stratovolcanoes (composite volcanoes) are tall conical mountains composed of lava flows and tephra in alternate layers, the strata that gives rise to the name. They are also known as composite volcanoes because they are created from multiple structures during different kinds of eruptions. Classic examples include Mount Fuji in Japan, Mayon Volcano in

975-445: Is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from a magma chamber below the surface. The process that forms volcanoes is called volcanism . On Earth, volcanoes are most often found where tectonic plates are diverging or converging , and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example,

1050-412: Is characterized by a rough, clinkery surface and is the typical texture of cooler basalt lava flows. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Pāhoehoe flows are sometimes observed to transition to ʻaʻa flows as they move away from the vent, but never the reverse. More silicic lava flows take the form of block lava, where

1125-514: Is derived from the name of Vulcano , a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan , the god of fire in Roman mythology . The study of volcanoes is called volcanology , sometimes spelled vulcanology . According to the theory of plate tectonics, Earth's lithosphere , its rigid outer shell, is broken into sixteen larger and several smaller plates. These are in slow motion, due to convection in

1200-584: Is expressed using the volcanic explosivity index (VEI), which ranges from 0 for Hawaiian-type eruptions to 8 for supervolcanic eruptions. As of December 2022 , the Smithsonian Institution 's Global Volcanism Program database of volcanic eruptions in the Holocene Epoch (the last 11,700 years) lists 9,901 confirmed eruptions from 859 volcanoes. The database also lists 1,113 uncertain eruptions and 168 discredited eruptions for

1275-537: Is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analysed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near

1350-471: Is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland , as well. Lava domes are built by slow eruptions of highly viscous lava. They are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount St. Helens , but can also form independently, as in

1425-593: The Aventine Triad – Ceres , Liber , and Libera – developed in association with the rise of plebeians to positions of wealth and influence. The gods represented distinctly the practical needs of daily life, and the Romans scrupulously accorded them the appropriate rites and offerings. Early Roman divinities included a host of "specialist gods" whose names were invoked in the carrying out of various specific activities. Fragments of old ritual accompanying such acts as plowing or sowing reveal that at every stage of

1500-617: The Cascade Volcanoes or the Japanese Archipelago , or the eastern islands of Indonesia . Hotspots are volcanic areas thought to be formed by mantle plumes , which are hypothesized to be columns of hot material rising from the core-mantle boundary. As with mid-ocean ridges, the rising mantle rock experiences decompression melting which generates large volumes of magma. Because tectonic plates move across mantle plumes, each volcano becomes inactive as it drifts off

1575-555: The GR 49 and GR 51. The Esterel mountains also host the Pierre & Vacances holiday village Cap Esterel. The Corniche d'Or, a touristic road along the coast and Île d'Or , links Saint-Raphaël and Cannes. 43°30′N 6°49′E  /  43.500°N 6.817°E  / 43.500; 6.817 This Provence-Alpes-Côte d'Azur geography article is a stub . You can help Misplaced Pages by expanding it . Volcano A volcano

SECTION 20

#1732773307797

1650-432: The Roman army spread his cult as far afield as Roman Britain . The important Roman deities were eventually identified with the more anthropomorphic Greek gods and goddesses, and assumed many of their attributes and myths. Many astronomical objects are named after Roman deities, like the planets Mercury , Venus , Mars , Jupiter , Saturn , and Neptune . In Roman and Greek mythology, Jupiter places his son born by

1725-599: The ancient Greeks and reinterpreted myths about Greek deities under the names of their Roman counterparts. The influence of Greek mythology likely began as early as Rome's protohistory . Classical mythology is the amalgamated tradition of Greek and Roman mythologies, as disseminated especially by Latin literature in Europe throughout the Middle Ages , into the Renaissance , and up to present-day uses of myths in fiction and movies. The interpretations of Greek myths by

1800-804: The core–mantle boundary , 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism , of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere . Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus. Mars has significant volcanoes. In 2009,

1875-834: The landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Kīlauea in Hawaii. Volcanic craters are not always at the top of a mountain or hill and may be filled with lakes such as with Lake Taupō in New Zealand. Some volcanoes can be low-relief landform features, with the potential to be hard to recognize as such and be obscured by geological processes. Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter , Saturn , and Neptune ; and mud volcanoes , which are structures often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when

1950-403: The war with Hannibal , any distinction between "indigenous" and "immigrant" gods begins to fade, and the Romans embraced diverse gods from various cultures as a sign of strength and universal divine favor. The absorption of neighboring local gods took place as the Roman state conquered neighboring territories. The Romans commonly granted the local gods of a conquered territory the same honors as

2025-605: The Archaic Triad – an unusual example within Indo-European religion of a supreme triad formed of two female deities and only one male. The cult of Diana became established on the Aventine Hill , but the most famous Roman manifestation of this goddess may be Diana Nemorensis , owing to the attention paid to her cult by J.G. Frazer in the mythographic classic The Golden Bough . What modern scholars call

2100-622: The Philippines, and Mount Vesuvius and Stromboli in Italy. Ash produced by the explosive eruption of stratovolcanoes has historically posed the greatest volcanic hazard to civilizations. The lavas of stratovolcanoes are higher in silica, and therefore much more viscous, than lavas from shield volcanoes. High-silica lavas also tend to contain more dissolved gas. The combination is deadly, promoting explosive eruptions that produce great quantities of ash, as well as pyroclastic surges like

2175-508: The Romans often had a greater influence on narrative and pictorial representations of myths than Greek sources. In particular, the versions of Greek myths in Ovid 's Metamorphoses , written during the reign of Augustus , came to be regarded as canonical . Because ritual played the central role in Roman religion that myth did for the Greeks, it is sometimes doubted that the Romans had much of

2250-613: The USGS defines a volcano as active whenever subterranean indicators, such as earthquake swarms , ground inflation, or unusually high levels of carbon dioxide or sulfur dioxide are present. The USGS defines a dormant volcano as any volcano that is not showing any signs of unrest such as earthquake swarms, ground swelling, or excessive noxious gas emissions, but which shows signs that it could yet become active again. Many dormant volcanoes have not erupted for thousands of years, but have still shown signs that they may be likely to erupt again in

2325-513: The best extant sources for Rome's founding myths . Material from Greek heroic legend was grafted onto this native stock at an early date. The Trojan prince Aeneas was cast as husband of Lavinia , daughter of King Latinus , patronymical ancestor of the Latini , and therefore through a convoluted revisionist genealogy as forebear of Romulus and Remus . By extension, the Trojans were adopted as

Massif de l'Esterel - Misplaced Pages Continue

2400-510: The boundary with the Yukon Territory . Mud volcanoes (mud domes) are formations created by geo-excreted liquids and gases, although several processes may cause such activity. The largest structures are 10 kilometres in diameter and reach 700 meters high. The material that is expelled in a volcanic eruption can be classified into three types: The concentrations of different volcanic gases can vary considerably from one volcano to

2475-402: The case of Lassen Peak . Like stratovolcanoes, they can produce violent, explosive eruptions, but the lava generally does not flow far from the originating vent. Cryptodomes are formed when viscous lava is forced upward causing the surface to bulge. The 1980 eruption of Mount St. Helens was an example; lava beneath the surface of the mountain created an upward bulge, which later collapsed down

2550-506: The city. These narratives focus on human actors, with only occasional intervention from deities but a pervasive sense of divinely ordered destiny. In Rome's earliest period, history and myth have a mutual and complementary relationship. As T. P. Wiseman notes: The Roman stories still matter , as they mattered to Dante in 1300 and Shakespeare in 1600 and the founding fathers of the United States in 1776. What does it take to be

2625-560: The community or Roman state. Heroism is an important theme. When the stories illuminate Roman religious practices, they are more concerned with ritual, augury , and institutions than with theology or cosmogony . Roman mythology also draws on Greek mythology , primarily during the Hellenistic period of Greek influence and through the Roman conquest of Greece , via the artistic imitation of Greek literary models by Roman authors. The Romans identified their own gods with those of

2700-636: The earlier gods of the Roman state religion . In addition to Castor and Pollux , the conquered settlements in Italy seem to have contributed to the Roman pantheon Diana , Minerva , Hercules , Venus , and deities of lesser rank, some of whom were Italic divinities, others originally derived from the Greek culture of Magna Graecia . In 203 BC, Rome imported the cult object embodying Cybele from Pessinus in Phrygia and welcomed its arrival with due ceremony . Both Lucretius and Catullus , poets contemporary in

2775-799: The enormous area they cover, and subsequent concealment under vegetation and glacial deposits, supervolcanoes can be difficult to identify in the geologic record without careful geologic mapping . Known examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States); Lake Taupō in New Zealand; Lake Toba in Sumatra , Indonesia; and Ngorongoro Crater in Tanzania. Volcanoes that, though large, are not large enough to be called supervolcanoes, may also form calderas in

2850-431: The flow is covered with angular, vesicle-poor blocks. Rhyolitic flows typically consist largely of obsidian . Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface . These violent explosions produce particles of material that can then fly from

2925-610: The formation of a submarine volcano off the coast of Mayotte . Subglacial volcanoes develop underneath ice caps . They are made up of lava plateaus capping extensive pillow lavas and palagonite . These volcanoes are also called table mountains, tuyas , or (in Iceland) mobergs. Very good examples of this type of volcano can be seen in Iceland and in British Columbia . The origin of the term comes from Tuya Butte , which

3000-585: The future. In an article justifying the re-classification of Alaska's Mount Edgecumbe volcano from "dormant" to "active", volcanologists at the Alaska Volcano Observatory pointed out that the term "dormant" in reference to volcanoes has been deprecated over the past few decades and that "[t]he term "dormant volcano" is so little used and undefined in modern volcanology that the Encyclopedia of Volcanoes (2000) does not contain it in

3075-466: The glossaries or index", however the USGS still widely employs the term. Previously a volcano was often considered to be extinct if there were no written records of its activity. Such a generalization is inconsistent with observation and deeper study, as has occurred recently with the unexpected eruption of the Chaitén volcano in 2008. Modern volcanic activity monitoring techniques, and improvements in

Massif de l'Esterel - Misplaced Pages Continue

3150-461: The gods Mars and Quirinus , who were often identified with each other. Mars was a god of both war and agriculture; he was honored in March and October. Quirinus was the patron of the armed community in time of peace. The 19th-century scholar Georg Wissowa thought that the Romans distinguished two classes of gods, the di indigetes and the di novensides or novensiles : the indigetes were

3225-415: The harvest. Jupiter , the ruler of the gods, was honored for the aid his rains might give to the farms and vineyards. In his more encompassing character he was considered, through his weapon of lightning, the director of human activity. Owing to his widespread domain, the Romans regarded him as their protector in their military activities beyond the borders of their own community. Prominent in early times were

3300-638: The influences of other cultures in response to social change. The earliest pantheon included Janus, Vesta , and the so-called Archaic Triad of Jupiter, Mars, and Quirinus, whose three patrician flamens were of the highest order . According to tradition, Numa Pompilius , the Sabine second king of Rome , founded Roman religion; Numa was believed to have had as his consort and adviser a Roman goddess or nymph of fountains and of prophecy, Egeria . The Etruscan-influenced Capitoline Triad of Jupiter, Juno and Minerva later became central to official religion, replacing

3375-492: The interior of a continent and lead to rifting. Early stages of rifting are characterized by flood basalts and may progress to the point where a tectonic plate is completely split. A divergent plate boundary then develops between the two halves of the split plate. However, rifting often fails to completely split the continental lithosphere (such as in an aulacogen ), and failed rifts are characterized by volcanoes that erupt unusual alkali lava or carbonatites . Examples include

3450-524: The late 6th century BC from the Cumaean Sibyl . Some aspects of archaic Roman religion survived in the lost theological works of the 1st-century BC scholar Varro , known through other classical and Christian authors. Although traditional Roman religion was conservative in ritual rather than dogmatic in doctrine, the meaning of the rituals they perpetuated could be adapted, expanded, and reinterpreted by accretions of myths, etiologies , commentary, and

3525-434: The mid-1st century BC, offer disapproving glimpses of Cybele's wildly ecstatic cult. In some instances, deities of an enemy power were formally invited through the ritual of evocatio to take up their abode in new sanctuaries at Rome. Communities of foreigners ( peregrini ) and former slaves (libertini) continued their own religious practices within the city. In this way Mithras came to Rome and his popularity within

3600-419: The mid-oceanic ridge is above sea level, volcanic islands are formed, such as Iceland . Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. The oceanic plate subducts (dives beneath the continental plate), forming a deep ocean trench just offshore. In a process called flux melting , water released from the subducting plate lowers the melting temperature of

3675-551: The modelling of the factors that produce eruptions, have helped the understanding of why volcanoes may remain dormant for a long time, and then become unexpectedly active again. The potential for eruptions, and their style, depend mainly upon the state of the magma storage system under the volcano, the eruption trigger mechanism and its timescale. For example, the Yellowstone volcano has a repose/recharge period of around 700,000 years, and Toba of around 380,000 years. Vesuvius

3750-415: The most dangerous type, are very rare; four are known from the last million years , and about 60 historical VEI 8 eruptions have been identified in the geologic record over millions of years. A supervolcano can produce devastation on a continental scale, and severely cool global temperatures for many years after the eruption due to the huge volumes of sulfur and ash released into the atmosphere. Because of

3825-438: The mud volcano is actually a vent of an igneous volcano. Volcanic fissure vents are flat, linear fractures through which lava emerges. Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically but are characterized by relatively gentle effusive eruptions . Since low-viscosity magma

SECTION 50

#1732773307797

3900-416: The mythical ancestors of the Roman people. The characteristic myths of Rome are often political or moral, that is, they deal with the development of Roman government in accordance with divine law, as expressed by Roman religion , and with demonstrations of the individual's adherence to moral expectations ( mos maiorum ) or failures to do so. Narratives of divine activity played a more important role in

3975-452: The next. Water vapour is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide . Other principal volcanic gases include hydrogen sulfide , hydrogen chloride , and hydrogen fluoride . A large number of minor and trace gases are also found in volcanic emissions, for example hydrogen , carbon monoxide , halocarbons , organic compounds, and volatile metal chlorides. The form and style of an eruption of

4050-876: The north side of the mountain. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 metres (100 to 1,300 ft) high. Most cinder cones erupt only once and some may be found in monogenetic volcanic fields that may include other features that form when magma comes into contact with water such as maar explosion craters and tuff rings . Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico , Caja del Rio

4125-549: The ocean surface as new islands or floating pumice rafts . In May and June 2018, a multitude of seismic signals were detected by earthquake monitoring agencies all over the world. They took the form of unusual humming sounds, and some of the signals detected in November of that year had a duration of up to 20 minutes. An oceanographic research campaign in May 2019 showed that the previously mysterious humming noises were caused by

4200-420: The ocean surface, due to the rapid cooling effect and increased buoyancy in water (as compared to air), which often causes volcanic vents to form steep pillars on the ocean floor. Hydrothermal vents are common near these volcanoes, and some support peculiar ecosystems based on chemotrophs feeding on dissolved minerals. Over time, the formations created by submarine volcanoes may become so large that they break

4275-471: The ocean's surface. In the deep ocean basins, the tremendous weight of the water prevents the explosive release of steam and gases; however, submarine eruptions can be detected by hydrophones and by the discoloration of water because of volcanic gases . Pillow lava is a common eruptive product of submarine volcanoes and is characterized by thick sequences of discontinuous pillow-shaped masses which form underwater. Even large submarine eruptions may not disturb

4350-468: The one that destroyed the city of Saint-Pierre in Martinique in 1902. They are also steeper than shield volcanoes, with slopes of 30–35° compared to slopes of generally 5–10°, and their loose tephra are material for dangerous lahars . Large pieces of tephra are called volcanic bombs . Big bombs can measure more than 1.2 metres (4 ft) across and weigh several tons. A supervolcano is defined as

4425-455: The operation a separate deity was invoked, the name of each deity being regularly derived from the verb for the operation. Tutelary deities were particularly important in ancient Rome. Thus, Janus and Vesta guarded the door and hearth, the Lares protected the field and house, Pales the pasture, Saturn the sowing, Ceres the growth of the grain, Pomona the fruit, and Consus and Ops

4500-486: The original gods of the Roman state, their names and nature indicated by the titles of the earliest priests and by the fixed festivals of the calendar, with 30 such gods honored by special festivals; the novensides were later divinities whose cults were introduced to the city in the historical period, usually at a known date and in response to a specific crisis or felt need. Arnaldo Momigliano and others, however, have argued that this distinction cannot be maintained. During

4575-425: The overlying mantle wedge, thus creating magma . This magma tends to be extremely viscous because of its high silica content, so it often does not reach the surface but cools and solidifies at depth . When it does reach the surface, however, a volcano is formed. Thus subduction zones are bordered by chains of volcanoes called volcanic arcs . Typical examples are the volcanoes in the Pacific Ring of Fire , such as

SECTION 60

#1732773307797

4650-619: The plume, and new volcanoes are created where the plate advances over the plume. The Hawaiian Islands are thought to have been formed in such a manner, as has the Snake River Plain , with the Yellowstone Caldera being part of the North American plate currently above the Yellowstone hotspot . However, the mantle plume hypothesis has been questioned. Sustained upwelling of hot mantle rock can develop under

4725-435: The same time interval. Volcanoes vary greatly in their level of activity, with individual volcanic systems having an eruption recurrence ranging from several times a year to once in tens of thousands of years. Volcanoes are informally described as erupting , active , dormant , or extinct , but the definitions of these terms are not entirely uniform among volcanologists. The level of activity of most volcanoes falls upon

4800-492: The same way; they are often described as "caldera volcanoes". Submarine volcanoes are common features of the ocean floor. Volcanic activity during the Holocene Epoch has been documented at only 119 submarine volcanoes, but there may be more than one million geologically young submarine volcanoes on the ocean floor. In shallow water, active volcanoes disclose their presence by blasting steam and rocky debris high above

4875-622: The solidified erupted material that makes up the mantle of a volcano may be stripped away that its inner anatomy becomes apparent. Using the metaphor of biological anatomy , such a process is called "dissection". Cinder Hill , a feature of Mount Bird on Ross Island , Antarctica , is a prominent example of a dissected volcano. Volcanoes that were, on a geological timescale, recently active, such as for example Mount Kaimon in southern Kyūshū , Japan , tend to be undissected. Eruption styles are broadly divided into magmatic, phreatomagmatic, and phreatic eruptions. The intensity of explosive volcanism

4950-543: The subject matter as represented in the literature and art of other cultures in any period. Roman mythology draws from the mythology of the Italic peoples and shares mythemes with Proto-Indo-European mythology . The Romans usually treated their traditional narratives as historical, even when these have miraculous or supernatural elements. The stories are often concerned with politics and morality, and how an individual's personal integrity relates to his or her responsibility to

5025-406: The surrounding areas, and initially not seismically monitored before its unanticipated and catastrophic eruption of 1991. Two other examples of volcanoes that were once thought to be extinct, before springing back into eruptive activity were the long-dormant Soufrière Hills volcano on the island of Montserrat , thought to be extinct until activity resumed in 1995 (turning its capital Plymouth into

5100-557: The system of Greek religious belief than among the Romans, for whom ritual and cultus were primary. Although Roman religion was not based on scriptures and their exegesis , priestly literature was one of the earliest written forms of Latin prose . The books (libri) and commentaries (commentarii) of the College of Pontiffs and of the augurs contained religious procedures, prayers, and rulings and opinions on points of religious law. Although at least some of this archived material

5175-434: The theory of plate tectonics. For example, some volcanoes are polygenetic with more than one period of activity during their history; other volcanoes that become extinct after erupting exactly once are monogenetic (meaning "one life") and such volcanoes are often grouped together in a geographical region. At the mid-ocean ridges , two tectonic plates diverge from one another as hot mantle rock creeps upwards beneath

5250-444: The thinned oceanic crust . The decrease of pressure in the rising mantle rock leads to adiabatic expansion and the partial melting of the rock, causing volcanism and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans, and so most volcanic activity on Earth is submarine, forming new seafloor . Black smokers (also known as deep sea vents) are evidence of this kind of volcanic activity. Where

5325-431: The underlying ductile mantle , and most volcanic activity on Earth takes place along plate boundaries, where plates are converging (and lithosphere is being destroyed) or are diverging (and new lithosphere is being created). During the development of geological theory, certain concepts that allowed the grouping of volcanoes in time, place, structure and composition have developed that ultimately have had to be explained in

5400-492: The volcano. Solid particles smaller than 2 mm in diameter ( sand-sized or smaller) are called volcanic ash. Tephra and other volcaniclastics (shattered volcanic material) make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geologic record. The production of large volumes of tephra is characteristic of explosive volcanism. Through natural processes, mainly erosion , so much of

5475-424: The volcanoes of the East African Rift . A volcano needs a reservoir of molten magma (e.g. a magma chamber), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice , typically a volcanic cone or mountain. The most common perception of

5550-458: Was available for consultation by the Roman senate , it was often occultum genus litterarum , an arcane form of literature to which by definition only priests had access. Prophecies pertaining to world history and to Rome's destiny turn up fortuitously at critical junctures in history, discovered suddenly in the nebulous Sibylline books , which Tarquin the Proud (according to legend) purchased in

5625-421: Was described by Roman writers as having been covered with gardens and vineyards before its unexpected eruption of 79 CE , which destroyed the towns of Herculaneum and Pompeii . Accordingly, it can sometimes be difficult to distinguish between an extinct volcano and a dormant (inactive) one. Long volcano dormancy is known to decrease awareness. Pinatubo was an inconspicuous volcano, unknown to most people in

#796203