Conway Reef , known since 1976 by its Fijian name Ceva-I-Ra Reef (pronounced [ˈðeβaiˈra] ), is a coral reef of the atoll type.
18-639: It is 2.5 km (1.6 mi) long in an east–west direction. In the middle of the reef there is a small sand cay , 1.8 metres (5 feet 11 inches) high, about 320 metres (1,050 feet) long, and 73 metres (240 feet) metres wide, with a land area of two hectares . Politically, it is in the Western Division and the Nadroga-Navosa province of the Republic of Fiji . However, geographically, it lies 450 km (280 mi) south-west of
36-509: A spacecraft in orbit, and depth is used for points below the surface. Elevation is not to be confused with the distance from the center of the Earth. Due to the equatorial bulge , the summits of Mount Everest and Chimborazo have, respectively, the largest elevation and the largest geocentric distance. In aviation, the term elevation or aerodrome elevation is defined by the ICAO as
54-503: A Japanese fishing vessel, Fuji Maru No. 2 , was wrecked on the reef. There have been three recent shipwrecks on the reef (1979, 1981 and 2008), the latest one is the Chinese fishing vessel San Sheng No. 168. The wreck of that ship lies on the northeast end of the reef. The stranded wreck of a coastal trading vessel lies 240 metres south of the centre of the cay. Access to the island should be attempted only at high tide , and only in
72-720: A separate entity for DXCC credit in amateur radio . Several Dxpeditions visited it as 3D2C in September 2012, 3D2CR in June 2019 and September 2021. and 3D2CCC in April 2024. Its former name is given to the Conway Reef Plate which is a tectonic microplate that extends on the sea bottom to the north of the reef. The Australian Plate is subducting under the New Hebrides Plate to produce an active seismic zone
90-428: A shallow draft tender . Extreme care must be taken to navigate the coral heads. Conway Reef is uninhabited, apart from some birds that appear to have almost no fear of humans. It offers the rare opportunity to experience diving and snorkeling in a virtually untouched underwater environment. In 1983 it was reported that there was some vegetation on the cay. In 1985 it was reportedly bare. The island counts as
108-484: Is its height above or below a fixed reference point, most commonly a reference geoid , a mathematical model of the Earth 's sea level as an equipotential gravitational surface (see Geodetic datum § Vertical datum ). The term elevation is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or
126-504: Is made up almost entirely of the skeletal remains of plants and animals – biogenic sediment – from the surrounding reef ecosystems. If the accumulated sediments are predominantly sand , then the island is called a cay ; if they are predominantly gravel , the island is called a motu . Cay sediments are largely composed of calcium carbonate (CaCO 3 ), primarily of aragonite , calcite , and high-magnesium calcite. They are produced by myriad plants (e.g., coralline algae , species of
144-471: Is much debate and concern over the future stability of cays in the face of growing human populations and pressures on reef ecosystems, and predicted climate changes and sea level rise . There is also debate around whether these islands are relict features that effectively stopped expanding two thousand years ago during the late Holocene or, as recent research suggests, they are still growing, with significant new accumulation of reef sediments. Understanding
162-575: The Hunter Fracture Zone and in concert with propagating back-arc extension, a volcanic Hunter Ridge that extends from southern Vanuatu to the area of Ceva-I-Ra. The convergence becomes oblique by Ceva-I-Ra as the Hunter Fracture Zone extends towards the Kadavu Islands of Fiji. Cay A cay ( / ˈ k iː , ˈ k eɪ / KEE , KAY ), also spelled caye or key , is a small, low- elevation , sandy island on
180-689: The green algae Halimeda ) and animals (e.g., coral , molluscs , foraminifera ). Small amounts of silicate sediment are also contributed by sponges and other creatures. Over time, soil and vegetation may develop on a cay surface, assisted by the deposition of sea bird guano . A range of physical, biological and chemical influences determines the ongoing development or erosion of cay environments. These influences include: Significant changes in cays and their surrounding ecosystems can result from natural phenomena such as severe El Niño–Southern Oscillation (ENSO) cycles. Also, tropical cyclones can either help build up or tear down these islands. There
198-421: The highest point of the landing area. It is often measured in feet and can be found in approach charts of the aerodrome. It is not to be confused with terms such as the altitude or height. GIS or geographic information system is a computer system that allows for visualizing, manipulating, capturing, and storage of data with associated attributes. GIS offers better understanding of patterns and relationships of
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#1732765892624216-557: The island in the 19th century: The brig Rapid , under Captain Arthur Devlin, ran aground on the reef at 0200 h on 14 January 1841, going at a speed of 7 knots with all its sails up: The crew member on lookout duty may not have been paying attention. And 14 years later, on the night of 26 January 1855, the ship Logan of New Bedford, under Captain Wells, was wrecked on Conway Reef (which he referred to as “Sandy Island Reef”). In 1964
234-582: The landscape at different scales. Tools inside the GIS allow for manipulation of data for spatial analysis or cartography. A topographical map is the main type of map used to depict elevation, often through contour lines . In a Geographic Information System (GIS), digital elevation models (DEM) are commonly used to represent the surface (topography) of a place, through a raster (grid) dataset of elevations. Digital terrain models are another way to represent terrain in GIS. USGS (United States Geologic Survey)
252-525: The main complex of the Fiji Islands. None of the other islands of Fiji are farther away from each other than 75 km (47 mi) (unless you count Rotuma Island , which is politically but not geographically part of Fiji). The closest land to Conway Reef is Hunter Island in the French territory of New Caledonia . Hunter Island is also claimed by Vanuatu . It lies 275 km (171 mi) to
270-406: The potential for change in the sediment sources and supply of cay beaches with environmental change is an important key to predicting their stability. Despite, or perhaps because of, all the debate around the future of cays there is consensus that these island environments are very complex and fairly fragile. Examples of cays include: Elevation The elevation of a geographic location
288-785: The surface of a coral reef . Cays occur in tropical environments throughout the Pacific , Atlantic , and Indian oceans, including in the Caribbean and on the Great Barrier Reef and Belize Barrier Reef . The Taíno word for "island", cairi , became cayo in Spanish and "cay" / ˈ k iː / in English (spelled "key" in American English). A cay forms when ocean currents transport loose sediment across
306-408: The surface of a reef to where the current slows or converges with another current, releasing its sediment load. Gradually, layers of deposited sediment build up on the reef surface – a depositional node . Such nodes occur in windward or leeward areas of reefs, where flat surfaces sometimes rise around an emergent outcrop of old reef or beach rock. The island resulting from sediment accumulation
324-564: The west-south-west ( WSW ) of Conway Reef. The reef was annexed by the United Kingdom in 1965, and incorporated into Fiji on independence. In 1838, the Royal Navy Captain Drinkwater Bethune of HMS Conway first came across the reef and recorded it; it was first mapped by several years later by a British captain named Denham, commanding HMS Herald . There were a couple of wrecks on
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