Selvagens Islands Nature Reserve - the lonely spot in Europe
von COOGOR Portugal
Selvagens Islands Nature Reserve belongs to the Autonomous Region of Madeira, and is therewith the southmost point of Portugal.
Selvagens (english: Salvation) Islands are a group of oceanic islands of volcanic origin. Its geological history is related to the opening and expansion of the Atlantic Ocean, a process that began some 200 million years ago and continues today. Installed in African continental slope, without ever having been in contact with the African continent, these islands are no more than rocky outcrops that form the immersed part of a single volcanic edifice that was born some 27 million years from deep ocean Atlantic. Consequently, comprise a geological heritage of great value and hold the title of first islands of Madeira to be created.
The northeast group of islands comprises Selvagem Grande (2,45 km²) and two smaller islets, Palheiro de Terra and Palheiro do Mar. Selvagem Grande has steep cliffs (70-90m). The interior is flat, with three extinct volcano cones (Pico da Atalaia (163m),Pico dos Tornozelos und Pico do Inferno), which are difficult to reach.
Selvagem Grande is formed from porous volcanic cinder, which gives rise to a soil with a vitreous surface and a microlithic structure. At the visible base of Selvagem Grande, one can observe phonolitic and nephelinic layers, on top of which a thick layer of yellow-coloured calcareous sand was deposited during the Miocene, a period during which the island was submerged. This sand, which infiltrated the fractures caused by volcanic explosions, was the source of the current calcareous dykes. Later, deposits were formed of ash, volcanic sands and lapilli under immersion.
The southwest group comprises Selvagem Pequena (20 ha) and Ilhéu de Fora (8 ha) as well as numerous smaller islets, including the Alto, Comprido and Redondo Islets, and also the tiny group of the Norte Islets. Selvagem Pequena is rather flat (5-10m above sea) with the Pico Veado as highest point (49m).
The Selvagem Grande and Selvagem Pequena islands lie 11 nautical miles (20 km) apart.
The first recorded official discovery of the Selvagens dates from 1438, since 1977 there is a lighthouse of 33m height on Selvagem Grande.
The islands are too small and too low to create a proper balanced climate of their own. Therefore they are very dry (recalling much of the Desertas Islands south-east of Madeira) and the temperature are higher than on Madeira. Occasionally winds from SW bring exceptionally heavy rainfall, on the other hand dry winds from the east carry dust and many migrant birds from Africa, especially during the migratory season. Usually it is very dry, and it has been known not to rain for three consecutive years!
Selvagems are a main breeding area for the white-faced storm petrels (Pelagodroma marina) with an estimated population of around 250.000 birds.
In case you are invited to go on land at Selvagem Grande, you may have a walk lead by a Nature Warden and buy/send a postcard from the post office further south of Portugal. Usually it is not permitted to land on Selvagem Pequena.
In order log log this earth cache, you may fulfill the following activities and questions, and send the result by mail to the owner:
of what geological origin (type of stone) where the first islands of Madeira?
What is the main component in phonolitic and nephelinic materials?
to which continent do Selvagens islands belong geologically?
If you stand at the wardens station, what consistency and color does the ground around it have, and why does it appear that way? Be specifiv to the tape of stone
Once you have identified this rock, tell me what type of rock it is. (Igneous, Metamorphic, or Sedimentary)
How many trees do you see from the wardens' station, and how does this relate to the climate? What relation to geology can be drawn?
Additional you may want to take a picture, showing the vessel with which you arrived, anchored at Selvagems. And please post your credential number.
(Pictures taken from wikimedia foundation, released unterCreative Commons Attribution/Share-Alike License)
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Logeinträge für Selvagens Islands Nature Reserve