42 résultats pour "limestone"

• House (architecture) I INTRODUCTION Trulli in Alberobello, Italy Alberobello, in the Apulia region of southeastern Italy, is noted for its unusual limestone houses known as trulli (from Greek trullos, dome).

  Fresco in the Villa of the Mysteries, PompeiiThe Villa of the Mysteries, Pompeii, Italy (built about 50 bc), featured a large hall with this mural encircling it. The mural ispainted in the Second Style of Roman painting. (Historians of art recognize four periods or styles in Roman wall painting.)The mural in the Villa of the Mysteries is thought to depict the initiation rituals of a mystery religion. For this reason, it hasbeen conjectured that the hall was used for cult rituals.Bridgeman Art Li...

• Coral - biology.

  Soft corals lack a distinct skeleton. Although they live in colonies, the individual polyps are fused into a complex body, usually strengthened by small lumps or spikesknown as sclerites, which are made of protein and calcite. Soft corals come in a variety of shapes, including undulating sheets, upright mushroomlike shapes, andbeautiful shapes that form branches. A number of other octocorals have skeletons made from a hard or horny protein, sometimes strengthened with more brittle calcareous dep...

• Acid Rain.

  the Adirondack Mountains of New York State, a quarter of the lakes and ponds are acidic, and many have lost their brook trout and other fish. In the middleAppalachian Mountains, over 1,300 streams are afflicted. All of Norway’s major rivers have been damaged by acid rain, severely reducing salmon and trout populations. E Plants and Animals The effects of acid rain on wildlife can be far-reaching. If a population of one plant or animal is adversely affected by acid rain, animals that feed on tha...

• Pyramids (Egypt) - geography.

  limestone debris left over from the construction work. When the workers had completed the pyramid and installed the pyramidion, or cap stone, ramps still covered the surface of the pyramid. As the workers dismantled the ramps from the top down, they slowly exposed the pyramid’s stone surface, which stonemasons smoothed and polished. When the ramp was gone, the pyramid wasdisplayed in its full majesty. B Interior The interior of the Great Pyramid is complex, with a series of passages leading t...

• Pyramids (Egypt) - History.

  limestone debris left over from the construction work. When the workers had completed the pyramid and installed the pyramidion, or cap stone, ramps still covered the surface of the pyramid. As the workers dismantled the ramps from the top down, they slowly exposed the pyramid’s stone surface, which stonemasons smoothed and polished. When the ramp was gone, the pyramid wasdisplayed in its full majesty. B Interior The interior of the Great Pyramid is complex, with a series of passages leading t...

• Alabama (state) - geography.

  indentations along the coast are measured, the state’s shoreline is 977 km (607 mi) long. It includes the shores of Mobile Bay, an inlet 56 km (35 mi) long at the mouthof the Mobile River. Barrier beaches partly block the entrance to the bay, leaving narrow openings on either side of Dauphin Island. Dauphin and other islands alongAlabama’s coast west of Mobile Bay are separated from the mainland by Mississippi Sound. D Climate Alabama has a humid subtropical climate, with short, relatively mild...

• Alabama (state) - USA History.

  indentations along the coast are measured, the state’s shoreline is 977 km (607 mi) long. It includes the shores of Mobile Bay, an inlet 56 km (35 mi) long at the mouthof the Mobile River. Barrier beaches partly block the entrance to the bay, leaving narrow openings on either side of Dauphin Island. Dauphin and other islands alongAlabama’s coast west of Mobile Bay are separated from the mainland by Mississippi Sound. D Climate Alabama has a humid subtropical climate, with short, relatively mild...

• Mesopotamian Art and Architecture I INTRODUCTION Mesopotamian Art and Architecture, the arts and buildings of the ancient Middle Eastern civilizations that developed in the area (now Iraq) between the Tigris and Euphrates rivers from prehistory to the 6th century BC.

  arts. III EARLY DYNASTIC PERIOD Figures from Tell AsmarCreated around 2700 bc, these stone figures are from the city of Tell Asmar in what today is Iraq. From the Temple ofAbu, the statuettes stood in watchful prayer with the wide, staring eyes often found in Sumerian sculpture. The figuresare in the Iraq Museum, Baghdād, Iraq.Art Resource, NY The first historical epoch of Sumerian dominance lasted from about 3000 BC until about 2340 BC. While earlier architectural traditions continued, a ne...

• Pennsylvania - geography.

  B Rivers and Lakes There are three major river basins in Pennsylvania: the Susquehanna, the Ohio, and the Delaware. Together they drain more than 90 percent of Pennsylvania’s landarea. Most of eastern and central Pennsylvania is drained by the Susquehanna and Delaware systems. The western part of the state is drained by the Allegheny andMonongahela rivers, which join at Pittsburgh to form the Ohio. In addition to the three major river basins, short streams flowing into Lake Erie drain the north...

• Pennsylvania - USA History.

  B Rivers and Lakes There are three major river basins in Pennsylvania: the Susquehanna, the Ohio, and the Delaware. Together they drain more than 90 percent of Pennsylvania’s landarea. Most of eastern and central Pennsylvania is drained by the Susquehanna and Delaware systems. The western part of the state is drained by the Allegheny andMonongahela rivers, which join at Pittsburgh to form the Ohio. In addition to the three major river basins, short streams flowing into Lake Erie drain the north...

• Geology.

  terminology. Today the geologic time scale is generally agreed upon and used by scientists around the world, dividing time into eons, eras, periods, and epochs. Everyfew years, the numerical time scale is refined based on new evidence, and geologists publish an update. Geologists use several methods to determine geologic time. These methods include physical stratigraphy, or the placement of events in the order of their occurrence,and biostratigraphy, which uses fossils to determine geologic time...

• Coral Reef.

  sensitive to particles of mud or sediment settling on them, which means that corals rarely grow close to rivers or other sources of sediment. In the sea, light is filteredout by depth, so reef-building corals can only grow in relatively shallow water. Even in the clearest oceans few reef-building corals grow below a depth of 80 to 100 m(260 to 328 ft). Although corals need nutrients, they cannot thrive in areas where there are large amounts of nutrients. Typically, microscopic organisms in the p...

• Texas - geography.

  D Climate Eastern Texas has a humid subtropical climate, while a semiarid low latitude climate prevails in central areas, and an arid low latitude climate in the extreme west. Alongthe coast the climate is much milder, with fewer extremes in temperatures. Hurricanes sometimes hit the coastal areas of Texas from late July through September, andtornadoes are common in north-central Texas in April and May. D1 Temperature Summers are hot throughout the state, and temperatures exceeding 35°C (95°F)...

• Texas - USA History.

  D Climate Eastern Texas has a humid subtropical climate, while a semiarid low latitude climate prevails in central areas, and an arid low latitude climate in the extreme west. Alongthe coast the climate is much milder, with fewer extremes in temperatures. Hurricanes sometimes hit the coastal areas of Texas from late July through September, andtornadoes are common in north-central Texas in April and May. D1 Temperature Summers are hot throughout the state, and temperatures exceeding 35°C (95°F)...

• Arkansas - geography.

  temperature rises to the upper 30°s C (lower 100°s F). C2 Precipitation Arkansas receives about 1,000 to 1,300 mm (about 40 to 50 in) of precipitation a year, and some areas receive even more. Most of the rain comes during winter andspring and at times is so heavy as to cause flooding. Snow is rare in the south but amounts to more than 250 mm (10 in) a year in the mountains. C3 Growing Season Arkansas has a long growing season. It averages 211 days for the state as a whole and ranges from 241...

• Arkansas - USA History.

  temperature rises to the upper 30°s C (lower 100°s F). C2 Precipitation Arkansas receives about 1,000 to 1,300 mm (about 40 to 50 in) of precipitation a year, and some areas receive even more. Most of the rain comes during winter andspring and at times is so heavy as to cause flooding. Snow is rare in the south but amounts to more than 250 mm (10 in) a year in the mountains. C3 Growing Season Arkansas has a long growing season. It averages 211 days for the state as a whole and ranges from 241...

• Kentucky - geography.

  The climate of Kentucky is characterized by warm or hot summers and cool winters. Throughout the year, temperatures do not vary greatly from place to place,although they are generally slightly lower in the Appalachian Plateaus region than elsewhere in the state. Average July temperatures are usually from 24° to 27°C (76°to 80°F) in the central and western areas and from 23° to 24°C (74° to 76°F) in the east. January averages range from below 1°C (34°F) in the northern Bluegrassregion to more tha...

• Kentucky - USA History.

  The climate of Kentucky is characterized by warm or hot summers and cool winters. Throughout the year, temperatures do not vary greatly from place to place,although they are generally slightly lower in the Appalachian Plateaus region than elsewhere in the state. Average July temperatures are usually from 24° to 27°C (76°to 80°F) in the central and western areas and from 23° to 24°C (74° to 76°F) in the east. January averages range from below 1°C (34°F) in the northern Bluegrassregion to more tha...

• United Kingdom - country.

  B Natural Regions and Topography The island of Great Britain can be divided into two major natural regions—the highland zone and the lowland zone. The highland zone is an area of high hills andmountains in the north and west. The lowland zone in the south and east consists mostly of rolling plains. The zones are divided by an imaginary line running throughEngland from the River Exe on the southwest coast to the mouth of the River Tees on the northeast coast. The lowland zone has a milder climat...

• Iranian Art and Architecture I INTRODUCTION Iranian Art and Architecture, the visual arts of Iran.

  The first great development of ancient Persian architecture took place under the Achaemenid dynasty during the Persian Empire, from about 550 to 330 BC. Remains of Achaemenian architecture are numerous, the earliest being ruins at Pasargadae, the capital city of Cyrus the Great. These ruins include two palaces, a sacred precinct, acitadel, a tower, and the tomb of Cyrus. The palaces were set in walled gardens and contained central columnar halls, the largest of which was 37 m (111 ft) in length...

• Vermont - geography.

  Forests cover 78 percent of Vermont. Most of the trees are deciduous, principally the maple, elm, birch, beech, oak, hickory, ash, cherry, and butternut. The state treeis the sugar maple, which provides Vermont’s famous maple syrup. Conifers are common in some mountain areas and include mainly the white pine, red spruce,hemlock, and cedar. A great variety of ferns have been found within the state. Among the more common wildflowers that grow in Vermont are anemones, arbutuses,violets, lilacs, dai...

• Vermont - USA History.

  Forests cover 78 percent of Vermont. Most of the trees are deciduous, principally the maple, elm, birch, beech, oak, hickory, ash, cherry, and butternut. The state treeis the sugar maple, which provides Vermont’s famous maple syrup. Conifers are common in some mountain areas and include mainly the white pine, red spruce,hemlock, and cedar. A great variety of ferns have been found within the state. Among the more common wildflowers that grow in Vermont are anemones, arbutuses,violets, lilacs, dai...

• Africa - history.

  Africa’s other major mountainous regions occur at the northern and southern fringes of the continent. The Atlas Mountains, a system of high ranges, extend for 2,200 km(1,400 mi) across Morocco, Algeria, and Tunisia, roughly parallel to the northern coast. These ranges enclose a number of broad inland basins and plateaus. In the west, theHigh (or Grand) Atlas contains Toubkal (4,165 m/ 13,665 ft), the highest peak of the system. Toward the east, the Atlas consists of two parallel ranges: the Tell...

• Africa.

  The highest elevations in Africa are found in the various ranges of East Africa. After Kilimanjaro, the next highest peaks are Mount Kenya (5,199 m/17,057 ft), north ofKilimanjaro in central Kenya; Margherita Peak (5,109 m/ 16,762 ft) in the Ruwenzori Range on the border between Uganda and the Democratic Republic of the Congo(DRC); Ras Dashen (4,620 m/ 15,157 ft) in the Ethiopian Highlands of northern Ethiopia; Mount Meru (4,565 m/ 14,977 ft), close to Kilimanjaro in Tanzania; and MountElgon (4,...

• Africa.

  The highest elevations in Africa are found in the various ranges of East Africa. After Kilimanjaro, the next highest peaks are Mount Kenya (5,199 m/17,057 ft), north ofKilimanjaro in central Kenya; Margherita Peak (5,109 m/ 16,762 ft) in the Ruwenzori Range on the border between Uganda and the Democratic Republic of the Congo(DRC); Ras Dashen (4,620 m/ 15,157 ft) in the Ethiopian Highlands of northern Ethiopia; Mount Meru (4,565 m/ 14,977 ft), close to Kilimanjaro in Tanzania; and MountElgon (4,...

• Africa - Geography.

  The highest elevations in Africa are found in the various ranges of East Africa. After Kilimanjaro, the next highest peaks are Mount Kenya (5,199 m/17,057 ft), north ofKilimanjaro in central Kenya; Margherita Peak (5,109 m/ 16,762 ft) in the Ruwenzori Range on the border between Uganda and the Democratic Republic of the Congo(DRC); Ras Dashen (4,620 m/ 15,157 ft) in the Ethiopian Highlands of northern Ethiopia; Mount Meru (4,565 m/ 14,977 ft), close to Kilimanjaro in Tanzania; and MountElgon (4,...

• Greek Art and Architecture - USA History.

  The struggle between these two city-states and their allies ultimately led to the Peloponnesian War (431-404 BC), which Sparta won. Despite this conflict, the 5th century, often called the Classical period, is usually considered the culmination of Greek art, architecture, and drama, with its highest achievements being the Temple ofZeus at Olympia, the Parthenon in Athens, and the plays of Athenian dramatists Aeschylus, Sophocles, Euripides, and Aristophanes. The 4th century, or Late Classical p...

• Hawaii (state) - geography.

  limestone along the coast. The volcanoes of the Hawaiian Islands are all so-called shield volcanoes, or lava domes. Unlike the volcanoes of Alaska and South America, those of Hawaii were notcreated by very explosive eruptions. Formed mostly by lava flows, they are great rounded mountain masses, rather than steep-sided cones. Mauna Kea, dormant forcenturies, is the highest mountain in the state. It rises to 4,205 m (13,796 ft) above sea level, and its summit is dotted with cinder cones formed by...

• Hawaii (state) - USA History.

  limestone along the coast. The volcanoes of the Hawaiian Islands are all so-called shield volcanoes, or lava domes. Unlike the volcanoes of Alaska and South America, those of Hawaii were notcreated by very explosive eruptions. Formed mostly by lava flows, they are great rounded mountain masses, rather than steep-sided cones. Mauna Kea, dormant forcenturies, is the highest mountain in the state. It rises to 4,205 m (13,796 ft) above sea level, and its summit is dotted with cinder cones formed by...

• Paleolithic Art I INTRODUCTION Cave Painting, Lascaux This portion of a cave painting in what is now Lascaux, France, was done by Paleolithic artists about 13,000 bc.

  Venus of WillendorfThis so-called Venus figurine from the area of Willendorf, Austria, is one of the earliest known examples of sculpture,dating from about 23,000 bc. The figure, which is carved out of limestone, is only 11.25 cm (4.5 in) high, and wasprobably designed to be held in the hand. It is believed the Venus may be a fertility symbol, which would explain theexaggerated female anatomy.Ali Meyer/Bridgeman Art Library, London/New York Paleolithic art usually is classified as either figura...

• Benin - country.

  French is the official language of Benin, but most people speak an African language. Each of the country’s ethnic groups has its own language. Fon is the most widelyspoken language. About 52 percent of the population professes traditional religious beliefs, chiefly Vodun, a belief in spirits. Arab merchants introduced Islam to the region, and today it isthe religion of some 20 percent of the people, most of whom live in the north. Christianity, especially Roman Catholicism, is the religion of ab...

• Carbon - chemistry.

  Graphite is black and slippery and conducts electricity. In graphite, the atoms form planar, or flat, layers. Each layer is made up of rings containing six carbon atoms.The rings are linked to each other in a structure that resembles the hexagonal mesh of chicken wire. Each atom has three sigma bonds (with 120° between any two ofthe bonds) and belongs to three neighboring rings. The fourth electron of each atom becomes part of an extensive pi bond system. Graphite conducts electricity,because th...

• Maya Civilization.

  destruction was directed mostly at temples in the ceremonial precincts; it had little or no impact on the economy or population of a city as a whole. Some city-states didoccasionally conquer others, but this was not a common occurrence until very late in the Classic period when lowland civilization had begun to disintegrate. Until thattime, the most common pattern of Maya warfare seems to have consisted of raids employing rapid attacks and retreats by relatively small numbers of warriors, most o...

• Maya Civilization - History.

  destruction was directed mostly at temples in the ceremonial precincts; it had little or no impact on the economy or population of a city as a whole. Some city-states didoccasionally conquer others, but this was not a common occurrence until very late in the Classic period when lowland civilization had begun to disintegrate. Until thattime, the most common pattern of Maya warfare seems to have consisted of raids employing rapid attacks and retreats by relatively small numbers of warriors, most o...

• Ethiopia - country.

  constitute about 6 percent of the population. The Somali, who live in the east and southeast, notably in the Ogadēn region, are about equal in number to the Shangalla.The Denakil inhabit the semidesert plains east of the highlands. The nonindigenous population includes Yemenis, Indians, Armenians, and Greeks. B Political Divisions Ethiopia is divided into nine regions composed of specific ethnic groups. The regions, which have a significant degree of autonomy, are Tigray; Afar; Amhara; Oromia;S...

• Egyptian Art and Architecture - USA History.

  The kings of the 1st Dynasty (2920 BC-2770 BC) were buried in the cemetery of their ancestors at Abydos in southern Egypt. Their burial sites were built of mud brick (bricks baked in the sun) and consisted of two parts: a tomb in the desert where the king was buried, and a rectangular funerary enclosure at the desert's edge, whererituals were performed. A pair of stone slabs called stelae marked the tombs and bore the name of the royal occupant. In the 2nd Dynasty (2770 BC-2649 BC), most r...

• South Korea - country.

  forest habitat, and overhunting. The Siberian tiger has not been sighted in the wild in South Korea since the 1920s; the Asiatic black bear can still be found in someremote mountain areas. Several species of deer are indigenous to the peninsula, including the roe deer, water deer, and Siberian musk deer. The musk deer, which hasbeen overhunted for its musk glands, is legally protected as a threatened species. Smaller mammals indigenous to the peninsula include the wild boar, red fox, badger,rabb...

• Tennessee (state) - geography.

  The climate of Tennessee is characterized by hot summers, mild winters, and abundant rainfall. C1 Temperature Average July temperatures range from less than 21° C (70° F) in the Blue Ridge region to 27° C (80° F) at Nashville and Memphis. Maximum daytime temperatures insummer often rise above 35° C (95° F) in central and western Tennessee. Daytime temperatures in the mountains rarely rise above 32° C (90° F). Summer nights tendto be warm and muggy in central and western Tennessee, but temperatu...

• Tennessee (state) - USA History.

  The climate of Tennessee is characterized by hot summers, mild winters, and abundant rainfall. C1 Temperature Average July temperatures range from less than 21° C (70° F) in the Blue Ridge region to 27° C (80° F) at Nashville and Memphis. Maximum daytime temperatures insummer often rise above 35° C (95° F) in central and western Tennessee. Daytime temperatures in the mountains rarely rise above 32° C (90° F). Summer nights tendto be warm and muggy in central and western Tennessee, but temperatu...

• Georgia (state) - geography.

  B Rivers and Lakes Most of the rivers of Georgia drain eastward to the Atlantic Ocean proper or southward to the Gulf of Mexico. Only a few flow northward to the Tennessee River, which isa major tributary of the Mississippi River. Most of the rivers flowing to the coasts are navigable by barges and small craft as far upstream as the Fall Line. The major river flowing to the Atlantic is the Savannah River, which, with the Tugaloo River, one of its headwaters, forms most of the state’s eastern bo...

• Georgia (state) - USA History.

  B Rivers and Lakes Most of the rivers of Georgia drain eastward to the Atlantic Ocean proper or southward to the Gulf of Mexico. Only a few flow northward to the Tennessee River, which isa major tributary of the Mississippi River. Most of the rivers flowing to the coasts are navigable by barges and small craft as far upstream as the Fall Line. The major river flowing to the Atlantic is the Savannah River, which, with the Tugaloo River, one of its headwaters, forms most of the state’s eastern bo...

• Cuba - country.

  Only two land mammals, the hutia, or cane rat, and the solenodon, a rare insectivore that resembles a rat, are known to be indigenous. The island has numerous batsand nearly 300 kinds of birds, including vultures, wild turkeys, quail, finches, gulls, macaws, parakeets, and hummingbirds. The bee hummingbird of Cuba is thesmallest bird in the world. Among the few reptiles are tortoises, caimans, the Cuban crocodile, and a species of boa that can attain a length of 3.7 m (12 ft). More than700 speci...