Byōbugaura ( 屏風ヶ浦 , Byōbugaura ) is an inlet on the northeast coast of Chiba Prefecture that ranges from Cape Inubō in Chōshi to Cape Gyōbumi in Asahi . Byōbugaura is an important part of the coastal area in Chiba Prefecture, as it connects the northern point of the Pacific Ocean coast at Chōshi to Kujūkuri Beach , which covers a large portion of the western side of the prefecture. The name of the inlet is formed from the word " byōbu ", the Japanese-style folding screen , and "ura", meaning an inlet. Byōbugaura resembles the White Cliffs of Dover on the English Channel . For this reason the inlet is sometimes called Tōyō no Dōbā ( 東洋のドーバー ) , or "Dover of the East". Byōbugaura is known for its long history of marine erosion .
24-527: Byōbugaura spans approximately 10 m (33 ft), with precipitous cliffs that reach an altitude of 60 m (197 ft). Three strata are clearly visible on the cliffs of the inlet: the reddish Kantō Loam Stratum at the top, the Katori Statum in the middle, the chalky-white Iioka Stratum prominently on the cliff face, and the Naarai Stratum at the base. The Kantō Loam Stratum is red and
48-438: A stratum , is the smallest formal unit in the hierarchy of sedimentary lithostratigraphic units and is lithologically distinguishable from other layers above and below. Customarily, only distinctive beds, i.e. key beds , marker beds , that are particularly useful for stratigraphic purposes are given proper names and considered formal lithostratigraphic units. In case of volcanic rocks, the lithostratigraphic unit equivalent to
72-526: A bed is a flow . A flow is “...a discrete, extrusive, volcanic rock body distinguishable by texture, composition, order of superposition, paleomagnetism, or other objective criteria.” A flow is a part of a member as a bed of sedimentary rock is a part of a member. In geotechnical engineering a bedding surface often forms a discontinuity that may have a large influence on the mechanical behaviour (strength, deformation, etc.) of soil and rock masses in tunnel , foundation , or slope construction. These are
96-400: A bed, a flow, is a discrete extrusive volcanic stratum or body distinguishable by texture, composition, or other objective criteria. As in case of a bed, a flow should only be designated and named as a formal lithostratigraphic unit when it is distinctive, widespread, and useful for stratigraphic correlation. A band is a thin stratum that is distinguishable by a distinctive lithology or color and
120-509: A combination of local deposition on the inclined surfaces of ripples or dunes , and local erosion . Graded beds show a gradual change in grain or clast sizes from one side of the bed to the other. A normal grading occurs where there are larger grain sizes on the older side, while an inverse grading occurs where there are smaller grain sizes on the older side. Bed thickness is a basic and important characteristic of beds. Besides mapping stratigraphic units and interpreting sedimentary facies,
144-442: A result of changes in environmental conditions. As a result, a bed is typically, but not always, interpreted to represent a single period of time when sediments or pyroclastic material accumulated during uniform and steady paleoenvironmental conditions. However, some bedding surfaces may be postdepositional features either formed or enhanced by diagenetic processes or weathering . The relationship between bedding surfaces controls
168-490: A stratum is generally one of a number of parallel layers that lie one upon another to form enormous thicknesses of strata. The bedding surfaces (bedding planes) that separate strata represent episodic breaks in deposition associated either with periodic erosion , cessation of deposition, or some combination of the two. Stacked together with other strata, individual stratum can form composite stratigraphic units that can extend over hundreds of thousands of square kilometers of
192-422: Is three-dimensional surface , planar or curved, that visibly separates each successive bed (of the same or different lithology ) from the preceding or following bed. Where bedding surfaces occur as cross-sections, e.g., in a 2-dimensional vertical cliff face of horizontal strata, are often referred to as bedding contacts . Within conformable successions, each bedding surface acted as the depositional surface for
216-536: Is composed of material from volcanic eruptions of Mount Fuji and Mount Hakone , and the white portions of the cliff face consist of easily eroded clay . Byōbugaura is noted in Japan for its historical and ongoing marine erosion due to the geological character of the inlet and the near-constant violent waves of the Pacific Ocean in the area. About 6 kilometres (3.7 mi) of land has been lost to erosion in
240-530: Is frequently used in textbooks, e.g., Collinson & Mountney or Miall. Both definitions have merit and the choice of which one to use will depend on the focus of the specific study on a case by case basis. Typically, but not always, bedding surfaces record changes in either the rate or type of accumulating sediment that created the underlying bed. Typically, they represent either a period of nondeposition, erosional truncation, shift in flow or sediment regime, abrupt change in composition, or combination of these as
264-518: Is useful in correlating strata. Finally, a key bed, also called a marker bed , is a well-defined, easily identifiable stratum or body of strata that has sufficiently distinctive characteristics, such as lithology or fossil content, to be recognized and correlated during geologic field or subsurface mapping. Bed (geology) In geology , a bed is a layer of sediment , sedimentary rock , or volcanic rock "bounded above and below by more or less well-defined bedding surfaces". A bedding surface
SECTION 10
#1732802142792288-532: The Chiba clan . The remains of the castle have been lost out to sea due to marine erosion. Byōbugaura makes up the southernmost part of Suigō-Tsukuba Quasi-National Park , but because of the danger of violent waves off the inlet there are few recreational facilities built in the area. Byōbugaura, due to its dramatic coastal scenery and location near Tokyo, has been extensively used as a filming location for television dramas , commercials , and film . The precinct of
312-499: The Earth 's surface. Individual stratum can cover similarly large areas. Strata are typically seen as bands of different colored or differently structured material exposed in cliffs , road cuts, quarries , and river banks. Individual bands may vary in thickness from a few millimeters to several meters or more. A band may represent a specific mode of deposition : river silt , beach sand , coal swamp , sand dune , lava bed, etc. In
336-545: The Tokai Shrine , above the inlet in Chōshi, has an important old-growth forest featuring the tabu species of laurel , castanopsis , and camellia , and is a Designated Natural Area of Chiba Prefecture. The areas above the inlet are also used for agricultural. The headland around Cape Inubō is cultivated for cabbage production. Byōbugaura can be reached by bus from JR East Chōshi Station . The inlet can be viewed at
360-534: The Chōshi Marina stop. 35°42′10″N 140°47′17″E / 35.70278°N 140.78806°E / 35.70278; 140.78806 Stratum In geology and related fields, a stratum ( pl. : strata ) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as either bedding surfaces or bedding planes . Prior to
384-538: The Pacific Ocean as early as the Kamakura period (1185–1333). Tsuneharu Kataoka (fl. 12th century), a grandson of the regional leader Taira no Tadatsune , used an area 100 metres (330 ft) in front of the present-day location of Iioka Lighthouse on Cape Gyōbumi to build Sanuki Castle . Kataoka plotted against the first Kamakura shōgun Minamoto no Yoritomo , and Kataoka, his family, and local supporters were defeated and killed at Sanuki Castle by members of
408-439: The accumulation of younger sediment. Specifically in sedimentology , a bed can be defined in one of two major ways. First, Campbell and Reineck and Singh use the term bed to refer to a thickness-independent layer comprising a coherent layer of sedimentary rock, sediment, or pyroclastic material bounded above and below by surfaces known as bedding planes. By this definition of bed, laminae are small beds that constitute
432-533: The analysis of bed thickness can be used to recognize breaks in sedimentation, cyclic sedimentation patterns, and gradual environmental changes. Such sedimentological studies are typically based on the hypothesis that the thicknesses of stratigraphic units follows a log-normal distribution . Differing nomenclatures for the bed and laminae thickness have been proposed by various authors, including McKee and Weir, Ingram, and Reineck and Singh. However, none of them have been universally accepted by Earth scientists. In
456-530: The gross geometry of a bed. Most commonly, the bottom and top surfaces of beds are subparallel to parallel to each other. However, some bedding surfaces of a bed are nonparallel, e.g., wavy, or curved. Differing combinations of nonparallel bedding surfaces results in beds of widely varying geometric shapes such as uniform-tabular, tabular-lenticular, curved-tabular, wedge-shaped, and irregular beds. Types of beds include cross-beds and graded beds . Cross-beds, or "sets," are not layered horizontally and are formed by
480-428: The past 700 years. In modern times, in the 63 years between 1888 and 1951 30 metres (98 ft) of land have been lost. Tetrapods have been extensively installed at Byōbugaura to establish breakwaters , and have softened the retreat of land. The area of Byōbugaura on the border of Chōshi features marine caves , but most have also been lost due to marine erosion. Byōbugaura was used as a defensive position overlooking
504-742: The practice of engineering geology, a standardized nomenclature is used for describing bed thickness in Australia, the European Union, and the United Kingdom. Examples of widely used bed thickness classifications include Tucker (1982) and McKee and Weir (1953). According to both the North American Stratigraphic Code and International Stratigraphic Guide, a bed is the smallest formal lithostratigraphic unit that can be used for sedimentary rocks. A bed,
SECTION 20
#1732802142792528-524: The publication of the International Stratigraphic Guide, older publications have defined a stratum as being either equivalent to a single bed or composed of a number of beds; as a layer greater than 1 cm in thickness and constituting a part of a bed; or a general term that includes both bed and lamina . Related terms are substrate and substratum (pl. substrata ), a stratum underlying another stratum. Typically,
552-438: The smallest (visible) layers of a hierarchical succession and often, but not always, internally comprise a bed. Alternatively, a bed can be defined by thickness where a bed is a coherent layer of sedimentary rock, sediment, or pyroclastic material greater than 1 cm thick and a lamina is a coherent layer of sedimentary rock, sediment, or pyroclastic material less than 1 cm thick. This method of defining bed versus lamina
576-586: The study of rock and sediment strata, geologists have recognized a number of different types of strata, including bed , flow , band , and key bed . A bed is a single stratum that is lithologically distinguishable from other layers above and below it. In the classification hierarchy of sedimentary lithostratigraphic units, a bed is the smallest formal unit. However, only beds that are distinctive enough to be useful for stratigraphic correlation and geologic mapping are customarily given formal names and considered formal lithostratigraphic units. The volcanic equivalent of
#791208