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21-471: Hirado Island was formed as a horst elevated from the sea in Pliocene period. Its bedrock features a mixture of the sea sedimentary rocks of Tertiary period, mixed and overlaid by the recent igneous rock . Due to being relatively young, the island is very hilly with large fraction of area over 200 meters elevation, and flat land is limited to marginal coastal plains. The coastline is highly indented and feature

42-622: A half-graben geometry. Other common geometries include metamorphic core complexes and tilted blocks . Examples of active continental rifts are the Baikal Rift Zone and the East African Rift . Divergent plate boundaries are zones of active extension as the crust newly formed at the mid-ocean ridge system becomes involved in the opening process. Zones of thickened crust, such as those formed during continent-continent collision tend to spread laterally; this spreading occurs even when

63-419: A dip to remain active and a new set of faults may be generated. Large displacements may juxtapose syntectonic sediments against metamorphic rocks of the mid to lower crust and such structures are called detachment faults . In some cases the detachments are folded such that the metamorphic rocks are exposed within antiformal closures and these are known as metamorphic core complexes . Passive margins above

84-574: A large cliffs along the entire north-west coast facing East China Sea , except for river mouths. The Hirado Island port was the primary departure point for the Japanese missions to Sui China and Japanese missions to Tang China in 7th-9th centuries. 16 October 1274, the Hirado Island was invaded by the detachment of the Mongol army as the part of Mongol invasions of Japan . During the 2nd invasion of 1281,

105-799: A weak layer develop a specific set of extensional structures. Large listric regional faults dipping towards the ocean develop with rollover anticlines and related crestal collapse grabens . On some margins, such as the Niger Delta , large counter-regional faults are observed, dipping back towards the continent, forming large grabenal mini-basins with antithetic regional faults. Areas of extensional tectonics are typically associated with: Rifts are linear zones of localized crustal extension. They range in width from somewhat less than 100 km up to several hundred km, consisting of one or more normal faults and related fault blocks. In individual rift segments, one polarity (i.e. dip direction) normally dominates, giving

126-439: Is greatly moderated by the surrounding sea, resulting in reduced seasonal and diurnal temperature variations. Horst (geology) In physical geography and geology , a horst is a raised fault block bounded by normal faults . Horsts are typically found together with grabens . While a horst is lifted or remains stationary, the grabens on either side subside . This is often caused by extensional forces pulling apart

147-471: Is offset along strike such as to create a gap e.g. a left-stepping bend on a sinistral fault, a zone of extension or transtension is generated. Such bends are known as releasing bends or extensional stepovers and often form pull-apart basins or rhombochasms . Examples of active pull-apart basins include the Dead Sea , formed at a left-stepping offset of the sinistral sense Dead Sea Transform system, and

168-472: The tsuyu ( 梅雨 , tsuyu , "plum rain") — the rainy season — occurring between early June (average:Jun.7) to late July (average:Jul.21). The island's weather is affected by the nearby Liman current  [ ja ] while being shielded from the warm Kuroshio Current by the Kyushu island, resulting in wetter and colder climate than should be expected at lower 30's latitudes. The climate of Hirado Island

189-492: The Ikitsuki Island . The island is served by the national Route 383 . Ferries are available for transfer to the lesser inhabited islands nearby. Hirado Island is located in the humid subtropical climate zone ( Köppen Cfa ), with four distinct seasons. The island rarely sees snowfall during the winter. Spring in Hirado Island starts off mild, but ends up being very humid. The summer tends to be Hirado's wettest season, with

210-532: The Russian Plain , Arabia , India and Central South Africa . This is in distinction to folded regions such as some mountain chains of Eurasia . The Midcontinent Rift System in North America is marked by a series of horsts extending from Lake Superior to Kansas . The Rwenzori Mountains in the East African Rift are an upthrown fault block, and are the highest non-volcanic, non-orogenic mountains in

231-487: The Sea of Marmara , formed at a right-stepping offset on the dextral sense North Anatolian Fault system. Back-arc basins form behind many subduction zones due to the effects of oceanic trench roll-back which leads to a zone of extension parallel to the island arc . A passive margin built out over a weaker layer, such as an overpressured mudstone or salt , tends to spread laterally under its own weight. The inboard part of

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252-599: The Table , Jura , the Dole mountains and the Rila – Rhodope Massif including the well defined horsts of Belasitsa (linear horst), Rila mountain (vaulted domed shaped horst) and Pirin mountain – a horst forming a massive anticline situated between the complex graben valleys of Struma and that of Mesta . Larger areas where the continent remains stable with horizontal table-land stratification can be considered horsts, such as

273-514: The collisional event is still in progress. After the collision has finished the zone of thickened crust generally undergoes gravitational collapse , often with the formation of very large extensional faults. Large-scale Devonian extension, for example, followed immediately after the end of the Caledonian orogeny particularly in East Greenland and western Norway . When a strike-slip fault

294-626: The crust. Horsts may represent features such as plateaus, mountains, or ridges on either side of a valley. Horsts can range in size from small fault blocks up to large regions of stable continent that have not been folded or warped by tectonic forces. The word Horst in German means "mass" or "heap" and was first used in the geological sense in 1883 by Eduard Suess in The Face of the Earth. Horsts may have either symmetrical or asymmetrical cross-sections. If

315-591: The geometries formed depend on the amount of stretching involved. Stretching is generally measured using the parameter β , known as the beta factor , where t 0 is the initial crustal thickness and t 1 is the final crustal thickness. It is also the equivalent of the strain parameter stretch . In areas of relatively low crustal stretching, the dominant structures are high to moderate angle normal faults, with associated half grabens and tilted fault blocks . In areas of high crustal stretching, individual extensional faults may become rotated to too low

336-507: The island once again. The Hirado Domain was established and Hirado Castle built under leadership of the Matsuura clan in 1599. The castle was razed in 1613 and re-built in 1704. In 1609–1641, a Dutch trading post was established on Hirado Island before being transferred to Dejima . From 1613, the ships of William Adams started operating from Hirado Island too, but the British trade mission

357-649: The island was an important rear base for the Mongols until being abandoned after the invasion failed. Since Muromachi period in 14th century, the island had become the hub for the Wokou pirates. In the development of the Nanban trade with Europe, the Portuguese trade station was operational on the island in 1550-1561 period. In 1584, the Spanish, British and Dutch traders started visiting

378-484: The normal faults to either side have similar geometry and are moving at the same rate, the horst is likely to be symmetrical and roughly flat on top. If the faults on either side have different rates of vertical motion, the top of the horst will most likely be inclined and the entire profile will be asymmetrical. Erosion also plays a significant role in how symmetrical a horst appears in cross-section. Horsts can form structural petroleum traps . In many rift basins around

399-790: The world, the vast majority of discovered hydrocarbons are found in conventional traps associated with horsts. For example, much of the petroleum found in the Sirte Basin , Libya (of the order of tens of billions of barrels of reserves) are found on large horst blocks such as the Zelten Platform and the Dahra Platform and on smaller horsts such as the Gialo High . The Vosges Mountains in France and Black Forest in Germany are examples of horsts, as are

420-504: The world. The Vosges Mountains in France were formed by isostatic uplift in response to the opening of the Rhine Graben , a major extensional basin. Extensional tectonics Extensional tectonics is concerned with the structures formed by, and the tectonic processes associated with, the stretching of a planetary body 's crust or lithosphere . The types of structure and

441-437: Was closed in 1623. In 2005, the city merged with the neighboring towns of Tabira , Ikitsuki , forming Hirado city , compromising all of Hirado Island as well as part of Kyushu. The Hirado Bridge traverses the over-570-meters-wide strait that connects the Hirado Island to Kyushu . The bridge was completed in 1977 and the transit fee was cancelled in 2010. Also, Ikitsuki Bridge (completed in 1991) connects Hirado Island to

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