Description
Lava Stone
Lava is rock in liquid form. Once magma reaches the Earth's surface or the seabed, it is called lava. Due to differences in magma composition, outflow rate, temperature, and chemical and mineralogical composition, there are several types of lava, each with its own behavior and characterized by a porous structure. Lava can have a destructive effect, but at the same time, it also has a creative effect. For instance, new land can be formed by lava; this is how the Hawaiian Islands in the Pacific Ocean were formed. Furthermore, cooled lava—after several centuries of weathering—is very fertile and can therefore be used effectively as agricultural land. The word 'lava' originates from the Italian language and is likely derived from the Latin word labes, which refers to the sliding or gliding of lava. The word was first used in its current meaning by Francesco Serao, a professor of medicine at the University of Naples, when he described the eruption of Mount Vesuvius in the period from May 14 to June 4, 1737. Serao believed that lava was a mixture of sand and earth that had been melted by the heat of the volcanic fire. He described “a stream of fiery lava” in comparison to the water and mud that flow down the volcano after heavy rain. Cooling viscous lava often accumulates in a volcanic shaft. Due to this blockage and the presence of gases in the lava, pressure builds up in the shaft. Eventually, an eruption occurs, producing large clouds of volcanic ash and gas, as well as pyroclastic flows. The most explosive eruptions are followed by a quieter period during which lava is expelled. If the lava is rich in silica, a slowly growing lava dome forms—a large, cushion-like structure full of cracks and fissures. The top and edges of a lava dome are usually covered with rock fragments, breccia, and ash. The hardened rock that forms from lava is called extrusive rock. The appearance and composition of different extrusive rocks vary greatly. If a lava flow of rhyolite cools rapidly, it can become obsidian. However, if it is filled with gas bubbles, it can also become pumice. If the same lava cools slowly, it becomes a light-colored solid rock simply called rhyolite.
The Khmer Empire, or Angkor Empire (referred to as Kambuja-desa in inscriptions from the period), was a civilization on the mainland of Southeast Asia between the 9th and 15th centuries, with its center of power in the western part of present-day Cambodia. Until the 13th century, Angkor was the most powerful and prosperous empire in Southeast Asia, its technology, art, and architecture unparalleled. At times, the Khmer Empire ruled large parts of what are now Cambodia, Laos, Thailand, and Vietnam, and received tribute from areas in modern-day Malaysia and Burma (Myanmar). During this period, the Khmers built reservoirs, canals, cities, and temples of dimensions that still inspire awe today. The most famous monuments from this period are Angkor Wat and other temples in the capital, Angkor. The culture and religion of the Khmer Empire were a blend of Hinduism and Buddhism, imported from India, with the original Southeast Asian religions, in which ancestor worship played a significant role. Brahmanism, Vaishnavism, Shaivism, and Mahayana Buddhism had spread to Southeast Asia from India. Until the 13th century, the primary cult in Angkor was that of the god with whom the king associated himself. This was usually Shiva, but in some cases, Vishnu. Shiva's popularity in the predominantly agricultural civilizations of Southeast Asia may have stemmed from his association with the earth, and therefore with ancestral spirits. Together with his consort Uma, Shiva (and the king, considered his mortal counterpart) ensured the fertility of the earth and rainfall. He also appeased the ancestral spirits. The king affirmed his special bond with the gods through his building program. Temples and cisterns often symbolized mountains, shrines, and bodies of water from sacred texts. The king also sponsored religious orders and hermitages. It is striking that many kings, regardless of which god they affiliated with, sponsored residences for Brahmins, Hindu ascetics devoted to Vishnu or Shiva, as well as Buddhist monks. Meanwhile, the population continued to follow many of the original animistic practices from before Indian influence. Many of these practices are still prevalent in the region today. The form of Buddhism practiced in Angkor was initially the Mahayana sect. The Theravada sect only emerged a century later. Theravada relies on the original teachings of the Buddha and places less emphasis on rituals and doctrine than Mahayana. Its relative simplicity, compared to Brahmanism and Mahayana Buddhism, may have contributed to the decline of the absolute kingship, surrounded by religious rituals, that was common in Angkor.
