Tuff known as volcanic tuff, is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is compacted into a solid rock in a process called consolidation. Tuff is sometimes erroneously called "tufa" when used as construction material, but properly speaking, tufa is a limestone precipitated from groundwater. Rock that contains greater than 50% tuff is considered tuffaceous. Tuff is a soft rock, so it has been used for construction since ancient times. Since it is common in Italy, the Romans used it for construction; the Rapa Nui people used it to make most of the moai statues in Easter Island. Tuff can be classified as either sedimentary or igneous rock, they are studied in the context of igneous petrology, although they are sometimes described using sedimentological terms. The material, expelled in a volcanic eruption can be classified into three types: Volcanic gases, a mixture made of steam, carbon dioxide, a sulfur compound Lava, the name of magma when it emerges and flows over the surface Tephra, chunks of solid material of all shapes and sizes ejected and thrown through the airTephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases.
Magma 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 solid chunks of material that can fly from the volcano. Chunks smaller than 2 mm in diameter are called volcanic ash. Among the loose beds of ash that cover the slopes of many volcanoes, three classes of materials are represented. In addition to true ashes of the kind described above, lumps of the old lavas and tuffs form the walls of the crater, which have been torn away by the violent outbursts of steam, pieces of sedimentary rocks from the deeper parts of the volcano that were dislodged by the rising lava and are intensely baked and recrystallized by the heat to which they have been subjected. In some great volcanic explosions, nothing but lumps of the old lavas and tuffs forming the walls of the crater etc. are emitted, as at Mount Bandai in Japan in 1888. Many eruptions have occurred in which the quantity of broken sedimentary rocks that mingled with the ash is great.
In the Scottish coalfields, some old volcanoes are plugged with masses consisting of sedimentary debris. These accessory or adventitious materials, however, as distinguished from the true ash, tend to occur in angular fragments, when they form a large part of the mass, the rock is more properly a "volcanic breccia" than a tuff; the ash ejecta vary in size from large blocks 20 ft or more in diameter to the minutest impalpable dust. The large masses are called "volcanic bombs". Many of them have ribbed or nodular surfaces, sometimes they have a crust intersected by many cracks like the surface of a loaf of bread. Any ash in which they are abundant is called an agglomerate. In those layers and beds of tuff that have been spread out over considerable tracts of land and which are most encountered among the sedimentary rocks, smaller fragments dominate and bombs more than a few inches in diameter may be absent altogether. A tuff of recent origin is loose and incoherent, but the older tuffs have been, in most cases, cemented together by pressure and the action of infiltrating water, making rocks which, while not hard, are strong enough to be extensively used for building purposes.
If they have accumulated subaerially, like the ash beds found on Mt. Etna or Vesuvius at the present day, tuffs consist wholly of volcanic materials of different degrees of fineness with pieces of wood and vegetable matter, land shells, etc. but many volcanoes stand near the sea, the ash cast out by them is mingled with marine sediments. In this way, ashy muds, sands, or in some cases ashy limestones are formed. Most of the tuffs found in the older marine formations contain admixtures of clay and sometimes fossil shells, which prove that they were beds spread out under water. During some volcanic eruptions, a layer of ash several feet in thickness is deposited over a considerable area; the showers of ash follow one another after longer or shorter intervals, hence thick masses of tuff, whether of subaerial or of marine origin, have a stratified character. The coarsest materials or agglomerates show this least distinctly. Apart from adventitious material, such as fragments of the older rocks, pieces of trees, etc. the contents of an ash deposit may be described as consisting of more or less crystalline igneous rocks.
If the lava within the crater has been at such a temperature that solidification has commenced, crystals are present. They may be of considerable size like the grey, rounded leucite crystals found on the sides of Vesuvius. Many of these are perfect and rich in faces because they grew in a medium, liquid and not viscous. Good crystals of augite and olivine are to be obtained in the ash beds of Vesuvius and of many other volcano
Gwladys Patience Épangue is a French taekwondo athlete. Representing France at the 2005 World Taekwondo Championships in Madrid, she won the silver medal in the welterweight division, losing to Hwang Kyung-Seon from South Korea in the final. At the 2007 World Taekwondo Championships in Beijing, she won a silver medal, losing to Hwang in the final again. Épangue represented her country in the –67 kg class at the 2008 Beijing Olympics and won a bronze medal. In 2009, Épangue won her first World Championship gold medal in welterweight at the 2009 World Taekwondo Championships in Copenhagen, Denmark. In Round of 32, she edged out South Korean's favorite Park Hye-Mi, who demolished Icelandic champion Auður Jónsdóttir 22–1 in the first round, in overtime. In the semifinal match, Épangue beat European rival Sandra Šarić of Croatia, 2008 European Champion and 4-time World Championship medalist, 6–1. Épangue withdrew from the 2012 Summer Olympics because of injury was replaced by her compatriot Anne-Caroline Graffe.
Athlete Biography at beijing2008 Gwladys Épangue at International Olympic Committee Gwladys Épangue at French Olympic Committee Gwladys Épangue at Olympics at Sports-Reference.com Gwladys Épangue at TaekwondoData.com
Tenroku was a Japanese era after Anna and before Ten'en. This period spanned the years from March 970 through March 973; the reigning emperors were Reizei-tennō and En'yū-tennō. February 970 Tenroku gannen: The new era name was created to mark an event or series of events; the previous era ended and the new one commenced in Anna 3, on the 25th day of the 3rd month of 970. 970: Fujiwara no Arihira became sadaijin, Fujiwara no Koretada became udaijin. 970: The sesshō and daijō-daijin Fujiwara no Saneyori died at the age of 71. 970: The sadaijin Fujiwara no Arihira died at age 79. 971: For the first time, a festival in honor of the kami of Iwashimizu Shrine was celebrated. 971: Koretada was created daijō-daijin. April 4, 972: Emperor En'yū's coronation at age 14 is organized by Koretada. 972: Koretada dies at age 49. Brown, Delmer M. and Ichirō Ishida, eds.. Gukanshō: The Future and the Past. Berkeley: University of California Press. ISBN 978-0-520-03460-0. Japan encyclopedia. Cambridge: Harvard University Press.
ISBN 978-0-674-01753-5. Nihon Ōdai Ichiran. Paris: Royal Asiatic Society, Oriental Translation Fund of Great Britain and Ireland. OCLC 5850691 Varley, H. Paul.. A Chronicle of Gods and Sovereigns: Jinnō Shōtōki of Kitabatake Chikafusa. New York: Columbia University Press. ISBN 9780231049405.