The island has a rectangular outline and is the remnant of three mostly eroded volcanoes. The highest point of the island, Quadrant Peak, directly overlies the coast. Inland Vindication Island features a rich vegetation, consisting of lichens and mosses, while various bird and penguin species breed along the coasts. There is no evidence of recent volcanic activity.
History and toponymy
Vindication and Candlemas Island were both discovered on 2 February 1775 by James Cook aboard HMSResolution.[1] In 1951–1952 the Argentine frigatesARAHércules and ARASarandí installed a marker on Vindication, claiming Argentine sovereignty over the island;[2] this is the first recorded landing on the island.[3] The British HMSProtector landed a party on Vindication in 1956–1957 as part of a larger operation in the South Sandwich Islands,[4] with other visits from the same ship in 1962[5] and 1964.[6] In 1961, the RRSShackleton landed a boat.[5] In May 1975, the Argentine research vessel ARAIslas Orcadas investigated seafloor communities in the channel between Vindication and Candlemas.[7] In January 2011, the MSGolden Fleece sent a landing party ashore at Chinstrap Point.[8]
The name "Vindication Island" refers to the fact that initially, James Cook's report of there being two islands (rather than one or three) was not believed.[9] Knob Point was charted in 1930 by Discovery Investigations personnel on Discovery II, and probably so named because a conspicuous height of land overlooks the point.[10]
Vindication Island is rectangular, with a 2.1 kilometres (1.3mi) long side and a 1.6 kilometres (0.99mi) short side.[15] The corners of the rectangle are the northwestern Crosscut Point cape, the northeastern Braces Point, the southeastern Chinstrap Point and the southwestern Knob Point.[16] The entire coastline is made up by steep cliffs[15] that rise above bouldery beaches; the only exception is the valley where Pothole Gulch enters the sea. Offshore lie numerous islets, such as Castor Rock and Pollux Rock south/southwest of Chinstrap Point and an unnamed islet west of Crosscut Point.[16]
The island's highest point is Quadrant Peak at 442m (1,450ft),[17] and lies in the southwestern corner of the island above Knob Point,[15] dropping almost directly into the sea.[16] A subsidiary peak above Crosscut Point is Splinter Crag, which rises 175 metres (574ft) above sea level. From there, the island slopes downwards in eastern direction.[15] This asymmetric shape is due to erosion by weather and sea being concentrated on the western side of the island.[18] The inland is formed by tablelands, ridges and creeks,[19] its surface covered with blocky debris from which lavas and pyroclastics emerge.[14]
The island is mostly ice-free[1] save for a shrinking area above 250 metres (820ft)[20] around Quadrant Peak;[16] in 1964 ice covered about 0.3 square kilometres (0.12sqmi).[21] Only about one tenth of the island is ice-covered,[22] because the small size of the island limits the area on which snow and ice can accumulate.[23] Separate ice bodies are found on the eastern side, where the main ice cap has left moraines.[19] There are three major drainages that all emanate from Quadrant Peak:[16] An unnamed one going northeast, Leafvein Gulch that runs eastward and Pothole Gulch to the southeast.[19] Leafvein Gulch during summer forms a waterfall across the coastal cliffs.[16] Pothole Gulch is fed by meltwater from the small ice cap. The shape of the unnamed drainage implies that it once extended farther west, before coastal erosion truncated it.[19]
Submarine structure
Vindication Island lies about 4.5 kilometres (2.8mi) west of Candlemas Island.[15] The Nelson Channel between the two islands is only about 24 metres (79ft) deep.[24] Both Candlemas and Vindication rise from the same submarine volcano, and are named the Candlemas Islands.[25] Around the islands the sea is less than 100 metres (330ft) deep,[26] forming a 12 kilometres (7.5mi) wide shallow platform with numerous shoals, islets and sea stacks.[27] They are remnants of eroded islands[26] and include Buddha Rock, Castor Rock, Cook Rock, Pollux Rock, Santa Rock, Saw Rock, Tomblin Rock and Trousers Rock. Most of the islets lie around Vindication.[28][29] Some of these rocks make up a series of shoals between the islands.[15] The shelf itself probably formed through marine erosion and scouring by icebergs.[30]
The volcano has a base diameter of more than 53 kilometres (33mi) at 2,500 metres (8,200ft)[28] and a total volume of about 2,200 cubic kilometres (530cumi).[28] Away from the shallow platform, the slopes of the volcano drop off steeply into the deep ocean.[27] East of Candlemas and abutting its southeastern side is a large 16 kilometres (9.9mi) wide submarine embayment, probably the remnant of a large sector collapse.[31] Two other structures interpreted as landslide scars lie north and south of the shelf,[32] which is scalloped by landslide scars.[33] The submarine slopes have wave-like bedforms in many places.[34] Smaller ridges emanate from the submarine volcano and are interpreted as parts of it,[35] while chutes emanating in all directions formed through mass wasting.[36] A submarine ridge at 1 kilometre (0.62mi) depth connects the group to Visokoi farther north.[37] West of Candlemas, monogenetic volcanoes are developed on the seafloor.[38]
Geology
East of the South Sandwich Islands, the South America Platesubducts beneath the Scotia Plate at a rate of 70 millimetres per year (2.8in/year). The subduction is responsible for the existence of the South Sandwich island arc, which is constituted by about eleven islands[39] in an eastward curving chain,[40] and submarine volcanoes such as Protector in the north and Adventure and Kemp in the south.[12] Most of the islands are stratovolcanoes of various sizes.[41] Geologically, Vindication Island resembles the older southeastern part of Candlemas Island.[17]
The island is made up by layers of lava flows, scoria and tuff,[17] intruded by dykes.[16] The tuffs have red, yellow and brown colours.[18] Some surfaces are formed by volcanic ash, while lava flows make up the islets. The oldest rocks are presumably found at the bottom of the cliffs, while lava flows at the surface are probably the youngest rocks.[14] Coastal erosion has removed most of the volcanic pile,[45] so that only about one-fifth of the original volcano remains.[18] The island was probably formed by three separate volcanic centres, two of which were centered offshore of the current island and are now completely eroded.[14]
The island is probably younger than one million years[46] and activity may have continued into the Holocene.[47] No historical activity is known from Vindication Island.[48] There is no evidence of recent activity[17] nor of any recently active fumaroles.[14]
Climate and vegetation
Vindication Island has a well-developed vegetation, consisting of algae[a], lichens[b] and mosses[c].[54] Soils on the island are less permeable than on other islands in the archipelago, allowing more water retention and thus facilitating vegetation growth.[55] The vegetation forms distinct plant communities, with mats and tall turfs.[49]Mites[d] and springtails[e] inhabit the vegetation.[54]
Leat, Philip T.; Tate, Alex J.; Tappin, David R.; Day, Simon J.; Owen, Matthew J. (September 2010). "Growth and mass wasting of volcanic centers in the northern South Sandwich arc, South Atlantic, revealed by new multibeam mapping". Marine Geology. 275 (1–4): 110–126. Bibcode:2010MGeol.275..110L. doi:10.1016/j.margeo.2010.05.001.
Leat, Philip T.; Day, Simon J.; Tate, Alex J.; Martin, Tara J.; Owen, Matthew J.; Tappin, David R. (September 2013). "Volcanic evolution of the South Sandwich volcanic arc, South Atlantic, from multibeam bathymetry". Journal of Volcanology and Geothermal Research. 265: 60–77. Bibcode:2013JVGR..265...60L. doi:10.1016/j.jvolgeores.2013.08.013.
