Maio

Maio
	Satellite image
Waters	Atlantic Ocean
Archipelago	Ilhas de Sotavento
Geographical location	15 ° 13 ′ N , 23 ° 10 ′ W Coordinates: 15 ° 13 ′ N , 23 ° 10 ′ W
length	26.1 km
width	17.3 km
surface	269 km²
Highest elevation	Monte Penoso ; 436 m
Residents	8400 ; 31 inhabitants / km²
main place	Cidade do Maio
	Map of the island

Maio ( Ilha do Maio , dt. " Island of the (month) May ") is one of the nine inhabited Cape Verde islands in the Atlantic .

geography

Maio belongs to the Ilhas de Sotavento archipelago (German: " Islands under the wind "). It is located east of the island of Santiago and southwest of Boa Vista . The desert island, dominated by only a few weathered volcanic vents and sitting on a limestone plinth, has an area of 269 km² and around 8,400 inhabitants, which results in a population density of 31 inhabitants per square kilometer. The highest point is Monte Penoso (436 m). The capital and port city is Cidade do Maio .

geology

Together with Sal, Maio is geologically the oldest island in the Cape Verde archipelago. Geomorphologically it is very much leveled, mainly through quaternary , marine abrasion . The hilly interior of the island has largely escaped this. Maio's geological career can be broken down as follows (from young to old):

Quaternary and Holocene sediments
Pliocene abrasion and renewed volcanism
Central intrusive complex
Volcanites
Angular discordance
Coruja formation
Carquiejo formation
Morro Formation - Pelagic Limestone
Bathala formation - oceanic crust

The foundation of Maios, raised up to 4000 meters in height and tilted in the process, consists of oceanic crust ( Bathala Formation - tholeiitic pillow lavas with NMORB composition , lava breccias , hyaloclastites and embedded sediments with a sub- Cretaceous minimum age of 113 ± 8 million years BP, i.e. end Aptium ), which is continuously overlaid by light, pelagic calcareous sediments of the Morro Formation from the Lower to Upper Cretaceous ( Valanginium to Barremium ). According to Muller et al. a. the oceanic crust below Maios is around 136 million years old BP and thus comes from the Valanginian. A comparable age (early Valanginium) is also suggested by Fourcade et al. a. assigned to the earliest sediments stored in the uppermost basalts on the basis of calpionellids and radiolarians .

The 180 to 350 meter thick sediment sequence of the Morro Formation in Maiolica facies (with radiolarians , aptychs and ammonites ) then goes over to the hanging wall into an increasingly shallower sediment environment, the Carquiejo Formation . The latter is a maximum of 90 meters thick and consists of heterogeneous clay slates , siltstones and thin-banked limestone from the period Albium to Cenomanium . The pelagic sedimentation environment was initially close to the calcite compensation depth , but deepened noticeably. Turbidite currents brought in continental and calcareous components.

With the beginning of the 300 meter thick Coruja Formation , pyroclastic tufa layers , sandstones and conglomerates appear for the first time over the pelagic limestone and point to a renewed volcanism. The tuffs are associated with rudites and thus prove an emergence of the island, also recognizable by clasts of Plutonic origin. They also prove the existence of an igneous episode before the beginning of actual volcanism on the island. At that time, Maio was likely to have undergone significant elevation and removal . The Coruja Formation is difficult to date, but it is definitely of a Middle Miocene age.

After leveling the sedimentary sequence, after a long hiatus discordant with a pronounced angular discordance, submarine, ankaramitic hyaloclastites and Neogene pillow lavas lay over the sediments. They were followed on the surface by ankaramitic lava flows and lava deltas with the associated volcanoclastic sediments (tuffs) and river sediments . The entire sequence is 15 to 7 million years old BP, it originated in the Middle and Upper Miocene ( Langhian to Messinian ).

In addition, tectonically induced narrowing occurred in the Tortonium in the period 9 to 7 million years BP - the Mesozoic sediments were folded and pushed internally towards the south with the formation of layer repetitions ( Monte Branco thrust ). In addition, at the beginning of the Tortonium 11 million years ago BP, the sediments had already been penetrated by larger storage passages.

The foundation Maios surrounds in a partial ring with a steep dip to the outside the plutonic intrusive of the so-called central intrusive ( engl. Central Intrusive Complex or abbreviated CIC ) - usually Essexite or pyroxenite , occasionally syenites , Carbonatites and transition flocks . The intrusives are very likely from the Lower Miocene and are likely to be 20 to 18 million years old BP ( Burdigalium ). The dome-like penetration of the intrusive complex on steep faults is likely to have occurred only after the tectonic movements in the Tortonium had been completed.

After a renewed erosion phase with the formation of a laterite horizon in places, a wide plateau arose in the Pliocene with lavas, olivine melilithites and nephelinites undersaturated with silica . Mighty, ankaramite lavas and pyroclastics emerged from topographically higher areas in the eastern part of the island; they flowed to the east through the valleys carved out of the Mesozoic strata.

The last section in Maio's geological development is of a non-volcanic nature. Quaternary beach deposits and other sediments such as alluvial fan sediments and aeolian sands of the Holocene laid discordant over the volcanic rocks, with the Quaternary deposits partially covering all previous series. The beach deposits can still be found up to a height of 70 meters above sea level .

history

The name Maio (Eng .: "May") derives from the date of discovery on May 1, 1460. A little later, semi-nomadic shepherd slaves were settled who produced beef cattle and hides on behalf of the Portuguese royal family to supply the slave ships of Cidade Velha . In the 16th century, cotton was added to the livestock industry and part of the population became sedentary. Finely woven cloths ( panos de Santiago ) were a valuable barter in continental Africa and were mainly used to buy up other slaves. After Santiago lost its dominant position in the 17th century, the natural salt pans were expanded and free settlers followed. To protect against pirate attacks and, last but not least, to persuade the English, who dominate the salt trade , to pay taxes , the Portuguese crown built a small fortress with a few cannons in the main town of Cidade do Maio (until 1975 Porto Inglês ).

Like the other Cape Verde Islands, Maio was repeatedly hit by famine, which sometimes forced the free population to sell themselves to America as slaves. The decline in salt production and increasing drought at the beginning of the 20th century was followed by a sustained movement of emigration .

After independence in 1975, survival had to be ensured through job creation programs in road construction and reforestation. The island largely devoid of vegetation in the interior has again a small but sustainable forestry and, after successful reforestation, the largest contiguous forest area in Cape Verde. This enables you to export firewood and charcoal to Praia .

administration

The island belongs to the southern group of the Cape Verde Islands, the Ilhas de Sotavento . The island's capital is Cidade do Maio .

Administratively, Maio is divided into a district of the same name ( concelho ) with only one municipality ( freguesia ) called Nossa Senhora da Luz .

Economy and tourism

Sea salt extraction on Maio

The main occupations are extensive animal husbandry , fishing and handicrafts (ceramics). Many families receive benefits from family members in Praia and overseas.

With its kilometer-long fine, light sandy beaches and wild, romantic rocky coastline, Maio has an impressive tourist potential that is little used as long as the transport of water sports equipment is difficult. The local airline TACV flies to Maio several times a week only from Praia. The short flight takes about 10 minutes. A closed ring road connects all important places with the island capital Cidade do Maio . The few visitors look forward to lonely beaches and long hikes and excursions into the interior of the island. Another attraction is the João Valente reef .

Individual evidence

↑ Martin Patriat, Cinthia Labails: Linking the Canary and Cape Verde hot spots, North West Africa . In: Marine Geophysical Researches . 27, number 3, 2006.
↑ R. Muller et al. a .: Age, spreading rates and spreading symmetry of the world's ocean crust . In: Geochemistry Geophysics Geosystems . 9 (Q04006), 2008, p. 1525-2027 .
↑ E. Fourcade et al. a .: Contribution à la datation de la croûte océanique de l'Atlantique central: Âge valanginien inférieur des basaltes océaniques et age neocomien des calcaires Maiolica de Maio (Îles du Cap Vert) . In: Marine Geology . tape 96 , 1990, pp. 31-44 .
↑ ^a ^b J. G. Mitchell et al. a .: On dating the magmatism of Maio, Cape Verde Islands . In: Earth and Planetary Science Letters . tape 64 , 1983, pp. 61-76 .
↑ CJ Stillman et al. a .: The geological history of Maio, Cape Verde Islands . In: Journal of the Geological Society . 139 no.3, 1982, p. 347-361 , doi : 10.1144 / gsjgs.139.3.0347 .

[1] Martin Patriat, Cinthia Labails: Linking the Canary and Cape Verde hot spots, North West Africa . In: Marine Geophysical Researches . 27, number 3, 2006.

[2] R. Muller et al. a .: Age, spreading rates and spreading symmetry of the world's ocean crust . In: Geochemistry Geophysics Geosystems . 9 (Q04006), 2008, p. 1525-2027 .

[3] E. Fourcade et al. a .: Contribution à la datation de la croûte océanique de l'Atlantique central: Âge valanginien inférieur des basaltes océaniques et age neocomien des calcaires Maiolica de Maio (Îles du Cap Vert) . In: Marine Geology . tape 96 , 1990, pp. 31-44 .

[Mitchell-4] J. G. Mitchell et al. a .: On dating the magmatism of Maio, Cape Verde Islands . In: Earth and Planetary Science Letters . tape 64 , 1983, pp. 61-76 .

[5] CJ Stillman et al. a .: The geological history of Maio, Cape Verde Islands . In: Journal of the Geological Society . 139 no.3, 1982, p. 347-361 , doi : 10.1144 / gsjgs.139.3.0347 .