Geography of the Canary Islands

The Canary Islands are located in the Atlantic Ocean between latitudes 29° 24′ 40″ N and 27° 38′ 16″ N, and longitudes 13° 19′ 54″ W of La Baja (in Roque del Este) and 18° 09′ 38″ W of Roque del Guincho (in El Hierro). It is 97 kilometers from Morocco and Western Sahara and about 1,400 kilometers from the Iberian Peninsula. It is, therefore, in the time zone of the 15th meridian. We are facing an archipelago of volcanic origin with eight islands (Tenerife, La Palma, La Gomera, El Hierro, Gran Canaria, Lanzarote, Fuerteventura and La Graciosa; and five smaller ones Alegranza, Montaña Clara, Lobos, Roque del Este and Roque del Oeste). All the smaller islands have 114 kilometers of coastline. The Canary Islands have an area of 7,447 km², and their coasts have a total length of 1,583 kilometers. In the 2001 census it has 1,694,477 inhabitants, which gives an average density of 228 h/km², well above the average for Spain (81 h/km²). Due to its geographical location, the Canary Islands are the southernmost region of Spain.

The Canary Islands comprise two provinces: Las Palmas, which includes the islands of Gran Canaria, Fuerteventura, Lanzarote and La Graciosa; and Santa Cruz de Tenerife, with the islands of Tenerife, La Gomera, El Hierro and La Palma. In addition, each major island is considered an administrative unit that is governed by an island council. It became an autonomous community on August 10, 1982. The capital of the autonomous community is shared between the cities of Santa Cruz de Tenerife and Las Palmas de Gran Canaria. It only has Spanish as its official language.

The Canary Islands have been known since ancient times, when they were called the Fortunate Islands thanks to the sweetness of their climate and the generosity of their land. During the Middle Ages the memory of their existence was lost and they had a particular history in which the Guanche population dominated the islands. They were rediscovered in 1312 by the Genoese sailor Lanceloto Malocello, who landed on the island to which he gave his name: Lanzarote. In the middle of the 14th century, various Majorcan expeditions reached these islands, such as those of Jaume Ferrer, but Biscayans and Andalusians also arrived. and Portuguese. In 1344, Pope Clement IV granted the islands to the Castilian infant Luis de la Cerda with the title of Prince of Fortune and the condition of undertaking a "crusade" of conquest. In 1402 Juan de Bethencourt and Gadifer de la Salle began the definitive conquest, but faced with the difficulties encountered, they asked Henry III of Castile for help, to whom they had to lend vassalage. In this way the islands enter the orbit of the crown of Castile. In 1477 the Catholic Monarchs obtained the right of conquest, which they began the following year with the captains Juan Rejón and Pedro de Algaba. The conquest of the last strongholds would last between 1492 and 1496 at the hands of Alonso Fernández de Lugo. The Canary Islands would become fundamental in the conquest of America starting in 1492. After joining the EU and despite the situation of the islands, very remote from the core of Europe, they integrated perfectly into the European Union.

Relief

The territory of the Canary Islands is very complex due to its island nature. It is a very recent volcanic archipelago (it is barely 30 million years old). The large volcanic edifices rest on large blocks of oceanic crust, and in the contact zone with the African continental crust. The tectonic weaknesses that gave rise to the faults and blocks through which magma arose occurred during the Alpine orogeny. They also seem to coincide with the presence of a hot spot, in which the mantle has an upwelling current. Thus, the arrangement of the islands reflects the network of faults present in the oceanic crust. They present active volcanism, although of little intensity. The bulk of the islands arise in the Miocene. Only El Hierro and the smaller islets are from the Quaternary.

The following table shows the highest mountains of each of the islands;

The geological history of the islands is very complex. We find several phases of lava flows that give a typical volcanic relief. The oldest are called ancient massifs (not to be confused with continental ancient massifs) that appear in Gran Canaria, La Gomera, the north of La Palma, the south of Fuerteventura, and sectors of Tenerife and Lanzarote. Somewhat more modern are the numbers that appear in El Hierro, the south of La Palma and sectors of Tenerife. Even in these oldest sectors, construction forms predominate over erosion and sedimentation. However, in structurally depressed areas, large masses of loosely rolled debris accumulate. During the great glaciations the Canary Islands had a more arid climate, which favored erosion and the appearance of debris on the slopes and ravines. However, the transport capacity of the waters is very limited and therefore they have not been evacuated. To a large extent these are regoliths.

The coasts are the ones that receive the most impetus from erosion, due to marine activity. There are very few accumulation areas, which translates into the existence of very few natural beaches. Large cliffs predominate. The beaches and dune fields are on abandoned abrasion platforms, witness to ancient sea levels.

The most characteristic thing about the Canary Islands are the ravines. This is the sporadic channel through which the current waters present on the islands are directed. Their route is short and they generally have a very marked rectilinear profile. Its channel is covered with debris carried by the waters.

Despite the mountainous nature of most of the islands, we also find important plains. Lanzarote and Fuerteventura are characterized by their glacis, which stand out a lot because they are the driest islands (as well as the oldest).

Relief of Tenerife

Tenerife is the largest of the Canary Islands, it has an area of 2,034 km² and 342 kilometers of coastline. It is a mountainous island, where the peak of Teide (3,718 m) is located, the highest altitude in Spain. It has a triangular shape, slightly elongated towards the northeast. It is located in the center of the archipelago. It had its last eruption in 1909: the Chinyero eruption. It is the island with the greatest geological complexity. It has places with a lot of personality such as Anaga, La Esperanza mountain, the Orotava valley or the Pedro Gil ridge (Dorsal mountain range). However, the central core of the island is the Cañadas del Teide, which is a large volcanic caldera. The relief of Tenerife is organized around three massifs: Anaga, Teno and Adeje; the Pedro Gil number and the central building.

Anaga occupies the north-east end. It has a predominant NE-SO address. It consists of a series of deep valleys and short-hauled narrow valleys, separated by narrow interflows, rectalles coming from the summits. This has been reduced to a narrow crest of low elevation due to erosion. Due to erosion we find multiple derivative forms. At the bottom of the ravines we find forms of accumulation of ravines. Its coasts are characterized by the almost continuous presence of cliffs. Anaga enlaza con la dorsal de Pedro Gil a través de la depression de La Vega de La Laguna. This valley was formed by the contribution of lavae on a topographic gap between the volcano of Teide and Anaga, being, in principle, an endorreic depression, which has propitiated the accumulation, to the collation, lagoon of derubis.

Teno is located at the northwest end of the island and has a general address NO-SE. It has a morphology similar to that of Anaga, but with ravines much more abrupt and deep. Its cliffs are also more spectacular. Here is the cliff of Los Gigantes. We also find the valley of El Palmar, filled with ruin deposits. This valley was formed by the temporary closure of the area due to a lava line. Teno links with the Teide through an active field of volcanoes. Here we see the summit of Abeque and the volcanoes of Garachico and Chinyero, which erupted in 1706 and 1909, respectively.

Adeje is south of Teno. It has less morphological relevance. It has a structural direction N-S.

Anaga and the central building link each other through the dorsal de Pedro Gil. It has a NE-SO address. Its morphology responds to the direct volcanic patterns, very little dismantled, although the deep ravines are not missing, product of erosion. However, these are not so deep and the interflows are wider. Here we find the valley of La Orotava, on the north side, and the valley of Güímar, on the south side.

The central building it's the largest extension and altitude. It's the one who welcomes the Teide. It is a very complex sector since here are the three structural directions present. It presents the typical volcanic relief, very little dismantled. Its southern back is the southern part of the island (the South Banks). Here we find an active recent Vulcanism. The Teide is characterized by a set of ramps that rise from the sea to the outer edge of the volcanic caldera. The central sector of the Teide consists of Las Cañadas del Teide, a tectonic depression that is a volcanic boiler on which more recent secondary buildings have been built: the peak of the Teide (3,718 m) and Pico Viejo (3,135 m).

Relief of La Palma

La Palma is a volcanic island, with the highest peaks in the Canary Islands, with the exception of the highest in Tenerife, such as Roque de los Muchachos (2,426 m). It recorded what was the most recent eruption in Spain until 2011, in 1971, on the Teneguía volcano, at the southern tip. In Roque de los Muchachos there is one of the most important astronomical observatories in the world. It has an area of 708 km² and 166 kilometers of coastline. It is located in the northwest corner of the archipelago. It has a characteristic almond shape, with the sharpest angle pointing south. La Palma has a long geological history. The northern half is the oldest, and three structural directions NE-SW, NW-SE and N-S converge. Set up an old bed. The maximum volcanic activity corresponds to the intersection point of these three structural directions. The southern half is the most recent and has a dominant N-S structural direction.

The set has a dome shape, whose materials are arranged radially, which reach greater development when they extend in favor of one of the fundamental directions; such as the Agua ravine, on the NE slope or the Las Angustias ravine, to the west. Active volcanism extends to the present day, although only occasionally. It occurs on the periphery of the massif: Puntallana (east slope), Barlovento (northeast end) and Puntagorda (west). The most important morphological accident is the Taburiente caldera. It is a volcanic caldera inside which the oldest materials on the island are found, along with some of the most modern. The caldera has a vertical wall with scarps of up to a thousand meters. Tectonic weaknesses have allowed erosion to open gaps that give way to the caldera. In this way, a fairly hierarchical hydrological network has been formed. The main collector that drains the caldera is the Las Angustias ravine. The southern sector of the island is known as Cumbre Vieja. Paradoxically, this is the youngest sector of the island, and therefore erosion has not yet done significant dismantling work. The most common ways are direct.

The ravines have very loose incisions. The largest number of volcanic phenomena on the island are concentrated here. The Teneguía volcano, which erupted in 1971, is on the southernmost tip of the island. The coast is notably cliffy, due to the sea strongly impacting poorly consolidated lava. Parts of the lava flows have been isolated off the coast, forming low islands. This phenomenon affects, above all, the western coast, where an island stands out that emerged from an underwater eruption in 1949. Cumbre Vieja links with the Taburiente caldera through the Cumbre Nueva ridge.

Relief of La Gomera

La Gomera is a volcanic island located in the center of the archipelago, SW of Tenerife. It has an area of 350 km² and 100 kilometers of coastline. Its maximum altitude is the height of Garajonay, 1,487 meters. It has a remarkably round shape, although with a slight NW-SE elongation, which is the dominant direction of the relief structures. The entire island is an ancient massif, which has not had volcanic manifestations throughout the Quaternary. Thus, erosion has profoundly transformed the island, with the ravines being very deep and developed, with narrow interfluves and sharp crests, and whose channels are covered by debris. The ravines are arranged radially around Garajonay. Garajonay has a dome shape, with much gentler slopes than the rest of the island. The other characteristic feature of the relief of La Gomera is its cliffed coast, only interrupted by the mouth of the ravines. These cliffs have walls between 100 and 300 meters, notably vertical, and even overhanging.

Relief of El Hierro

El Hierro is a volcanic island located at the southwestern end of the archipelago. With an area of 264 km² and 110 kilometers of coastline, it is the smallest of the inhabited islands in the archipelago and the least populated. Its most notable altitude is Malpaso, 1,501 meters. Orchilla Point is the westernmost point of the island and was the 0º meridian until it was replaced by the Greenwich meridian. Just opposite is Roque del Guincho, the westernmost point of Spain. El Hierro is the youngest island in the archipelago. It has a bent elbow shape that corresponds to the three directions present on the island NE-SO, NW-SE and N-S. Each of these directions corresponds to a ridge, which is found in the center of the island. Despite being a recent island, no historical eruptions were known on it until 2011, when the underwater eruption of La Restinga took place. The relief is organized around the three large ridges and the Gulf.

The eastern ridge is the most developed. It has a NE-SW direction and is articulated around the Ventejís stratovolcano (1,137 m), and extends through the summit of Montaña, Pedraje, Pelota and Cepones. Its relief is characterized, despite its youth, by deep ravines. At the southwestern end it links with the Nisdafe plateau. To the southeast we find the coast of Las Playas, and to the northwest the cliffs of Tibataje, which gives way to the Gulf.

La Western It's just a little lower than the eastern one, but it's more altitude. Here is Malpaso. It has a NO-SE structural direction. On the northern side is the Gulf and in the southern El Julan. The set is solved in a series of shallow ravines. At the western end we find the gentle slope of La Dehesa, which ends on high cliffs. Here we find the tip of Orchilla.

La south has less development. It has a structural N-S address. It's the youngest part of the island, so the erosion, here, has incided less. In La Restinga we find the southernmost point in Spain: Punta de los Saltos.

The Gulf It is a large lava platform that is located at the NO of the island and is bordered by a spectacular mountainous cliff shaped arch, which today has a strewn look, but it was a powerful cliff, which has been dismantled by marine action.

Relief of Gran Canaria

Gran Canaria is a volcanic island located in the center of the archipelago. It is shaped like a scallop shell, has an area of 1,530 km², 256 kilometers of coastline and a maximum altitude of 1,949 meters, which is reached at Pico de las Nieves. It is the third island of the archipelago in area (after Tenerife and Fuerteventura) and altitude (after Tenerife and La Palma). The volcanic edifice surpassed sea level 14 million years ago, the last eruption having taken place about 3,000 years ago, so eruptions in the future are not ruled out. The entire island, except the Isleta peninsula, is an ancient massif, although the oldest materials are found to the southwest and the youngest to the northeast. Thus, the volcanic forms are more dismantled in the southern half called "Paleocanaria" or "Tamarán", here the ravines are deeper, with flat bottoms and the interfluves presenting more marked crests; the northern half of the island called "Neocanaria" It presents a less eroded relief. In the Paleocanary area we find vertical walls of up to 500 and 600 meters, and important cones of debris, a product of erosion, which can form wide alluvial fans, as is the case of the Fataga ravine, to the south, where they are found. the dunes of Maspalomas. The ravines in the south have a flat bottom, in contrast to those in the north, which are V-shaped. The ravines are organized radially around the central summit, a plateau between large volcanic calderas that occupy the center of the island. From here, three ravines start towards the west, through the interior of the Caldera de Tejeda, which when they converge form the La Aldea ravine, a group that constitutes the largest hydrographic basin on the island. There are other volcanic calderas, such as Tirajana, which has escarpments of up to 900 meters in the Los Caideros area. This caldera is covered in debris. The Bandama caldera is the most spectacular example, in the Canary Islands, of a phreatic explosion. Except for specific sections, the coast is characterized by the continuous presence of cliffs mainly in the northern and western sectors, especially in this last area where the cliffs usually exceed 500 meters. The east and south coasts are much lower, with numerous sandy beaches.

Relief of Fuerteventura

Fuerteventura is a volcanic island located to the east of the archipelago. It has an elongated shape in a NNE-SSO direction. It is separated from the island of Lanzarote, to the north, by the island of Lobos and the La Bocaina Strait. It has an area of 1,690 km² and 304 kilometers of coastline, which makes it the second largest island in the archipelago (after Tenerife), and its maximum altitude is only 807 m and is reached in Jandía. It is, therefore, one of the low islands, which means that it does not have a vigorous volcanic relief, nor do ravines fit into its surface. In the central west of the island the oceanic crust emerges: Morrete de Yeseros, Cuchillo de Agua Dulce (Betancuria massif). The southern two thirds are a very dismantled ancient massif, although here, on the Jandía peninsula, the highest heights are found. The northern third is an active volcano field. Volcanic badlands are characteristic, such as those in the north, Arena, Chico, Grande, Jacomar and the three small volcanoes of Pájara. The north of the island is divided between the badlands of Bayuyo and the jable of Corralejo, one of the most important dune fields in the Canary Islands. The interior plain is one of the most characteristic regions of the island. It extends from Montaña Quemada, in the north, to the Tarajal de Sancho valley in the south. Despite the general flatness of the island, the interfluves between ravines are very narrow and vertical: knives, exceeding 400 meters. Place names with sharp reminiscences dominate on the island: knives, needles, or nose, when the tip is rounded. The ravines, thus, are flat-bottomed. The Jandía peninsula is the most outstanding unit of Fuerteventura. It is a narrow and relatively high ancient massif that has the largest escarpments on the island. It presents a generalized gabled ravine. To the west extends the plain of Punta Jandía. It connects with the island through the isthmus of La Pared, where we find an important dune field.

Relief of Lanzarote

Lanzarote is a volcanic island located at the eastern end of the archipelago. It extends its domain over three islands located to the north: La Graciosa, Montaña Clara and Alegranza. It is separated from the island of Fuerteventura, to the south, by the island of Lobos and the La Bocaina Strait. It has an area of 845 km², 191 kilometers of coastline and a maximum altitude of 670 meters, which is reached in Peñas de Chache, located to the north. Most of the island is an active volcano field, except for the northern end, where we find the ancient massif of Famara, and another smaller one to the southeast: the Ajaches. The volcanic edifices are intensely eroded, but unlike other islands the interfluves are hilly and not ridged. The Famara massif dips gently to the east, in the west it rises into the Famara cliff that becomes a spectacular cliff. It presents a series of volcanic cones: Quemada de Orzola, La Cerca, Los Helechos and La Quemada. The Ajaches massif has a structure very similar to that of Famara, also with a high escarpment to the west, but instead of facing the sea, a powerful lava field extends at its feet that has blocked the old ravines. They are the Femés and Fena valleys. Between these two massifs extends a large volcanic field, very recent, in which the depressions left by the lava rivers are used by running waters. This entire lava field is organized around the Timanfaya natural park, and its eruptions from the 18th and 19th centuries. The most important eruption began on September 1, 1730 and ended on April 16, 1736. From this eruption arose the current cones of Timanfaya and Pico Partido, and the Montañas de Fuego, composed of a series of clustered cones. The relief is therefore typically volcanic structural. Corded lava badlands abound, with tunnels and caves (Cueva de los Verdes and Jameos del Agua). Timanfaya (The Volcano) is located, unlike other islands, on the western coast of the island. Between Timanfaya and the Ajaches lies La Geria. Part of these flows are covered with sand, which forms active dune fields.

Minor Islands

Relief of La Graciosa

La Graciosa is part of a group of islands and islets that emerged during the Quaternary called the Chinijo Archipelago, composed of La Graciosa, Alegranza, Montaña Clara and the Roques del Este and del Oeste. It is northeast of Lanzarote, an island on which it depends administratively and from which it is separated by an arm of sea known as El Río. La Graciosa has an area of 27 km² and a maximum altitude of 266 meters. In the volcanic landscape of La Graciosa you can find craters such as Montaña Amarilla; 'malpei' areas, formed by lava emissions that emerged from the fissures of the volcanic cones; extensive flows that flow from the cinder cones.

The climate is predominantly dry with contrasting temperatures throughout the year, around 20°C and with little rainfall (140mm per year). Due to its low altitude, the Montaña de las Agujas with 266m, La Graciosa and the rest of the archipelago do not receive the contribution of humidity from the dominant northeast winds (trade winds). Different sedimentary episodes allowed the accumulation of fine-grained materials such as sand, silt and clay. These soils have great ecological interest but present serious problems as agricultural lands, which have constituted a limiting factor for human settlement.

Water resources

Currently in the Canary Islands there are no rivers per se, there are ravines, as well as streams with little flow, but of a perennial nature, such as El Cedro, on the island of La Gomera, which has flow throughout the year, which turns it, in fact, into a river. This is due to the permeability of the land, the lack of rainfall in many areas, the high slope of the water courses and a dominant rainwater feeding, which The snow on the highest peaks is not enough. But this situation is also a product of anthropogenic action. Until recently, except in Fuerteventura, Lanzarote and El Hierro, there were a certain number of permanent streams on all the islands, but the needs to collect water for human consumption have cut off the regularity of these streams. This need has made the exploitation of groundwater essential. The swamps cut the surface course, the wells lower the base level of the rivers, causing their superficial disappearance. The most common form of groundwater extraction is the filter gallery. The continuous growth of water needs, since the end of the XIX century, has caused the Canary Islands to be deficient in water, and need resort to desalination of sea water for human consumption. This process has been especially important in Lanzarote, Fuerteventura, Gran Canaria and Tenerife. In the Canary Islands the waters are, for the most part, underground. Although there are notable differences, in general volcanic materials are mostly permeable. The topological characteristics of badlands make runoff difficult and favor infiltration. Added to the natural porosity of volcanic rocks is the presence of multiple cracks that appear during the cooling process. Although there are endorheic areas, there are hardly any natural lakes. The use of springs (springs in local terminology) only has a certain importance in La Palma and La Gomera, but not even here is it a significant percentage. Wells and galleries are the main way of exploiting water on the islands. The construction of swamps to take advantage of surface waters is relatively recent, but this system is very ineffective, since the surface waters are irregular, there are no large catchment vessels on the islands and their substrate is very permeable.

The eastern islands are the driest in the Archipelago, a fact that has made them pioneers in water desalination. In fact, the first desalination plant in Spain^{[citation required]} was installed in Lanzarote in 1964. Currently, practically all of the water consumed in Lanzarote and Fuerteventura, and to a lesser extent in Gran Canaria, comes from desalination^{[citation required]}. Globally, almost a quarter of the water supply in the Canary Islands comes from plants that purify seawater.^{[citation required]}

Climate

The dominant climate in the Canary Islands is dry and humid subtropical, but due to its position in the middle of the Atlantic and its relief, there are numerous very significant microclimates. In reality, the Canary Islands are halfway between the western circulation zone generated by the polar front and the subtropical high pressures generated in the Azores. Although the trade wind regime is dominant, the seasonal variation of the Azores anticyclone allows the arrival of polar air masses, and the proximity to the African continent, at the height of the Sahara, allows the arrival of dry and continental tropical air masses. warm, often accompanied by suspended dust (haze). The main centers of action are the Azores anticyclone and the position of the Intertropical Convergence Zone, but also, and secondarily, the polar front and the Saharan low pressures.

The Canary Islands are, preeminently, under the dominance of the trade winds coming from the eastern flank of the Azores anticyclone. These winds are very constant and have a regular speed of between 20 and 22 km/h, and a component that varies between the east and the northeast. These winds blow almost permanently. In summer they have a frequency of up to 90%, while in winter this proportion is reduced to 50%. The most interesting feature of these winds is their stratification into two layers, one low and humid and the other high and dry. This circumstance generates a thermal inversion of variable limits and whose most striking consequence is the appearance of a "sea of clouds" on the slopes oriented to the dominant winds. The sea of clouds creates a greenhouse effect that contributes to the thermal stability of low areas. In addition, these clouds prevent large amounts of sunlight from reaching the sea, which contributes to the stability of the cold Canary current, a marine current that softens the temperatures of the archipelago. Thanks to the thermal inversion, which prevents the rise of humidity, the lower layers of the atmosphere have a high relative humidity index, especially between 500 and 1200 meters. This humidity index can reach 100% but without causing precipitation, in what is called horizontal rain.

In addition to the trade winds on mountainous islands, local winds must be taken into account, both the sea breeze and the winds that ascend (adiabatic) towards the summits during the day, or descend (katabatic) towards the coast during the day. evening.

The climate of the Canary Islands is tempered by the cold Canary Current. This marine current coming from the north is a bifurcation of the Gulf Stream, which when it meets the Azores divides into two branches, a warm one that goes north and a cold one that descends to the Canary Islands, after passing through the southern coast of Portugal. and the western part of North Africa. In the Canary Islands, the trade winds tend to move surface waters towards the center of the Atlantic, favoring the rise of cold waters, which generally travel deeper. The presence of the cold current attenuates the two-layer stratification of the trade winds.

The nearby presence of the Sahara Desert also has its influence on the Canarian climate. It is manifested by the advection of very warm, dry air with large amounts of suspended dust, which makes visibility difficult (haze). They are generally strong winds with a very marked east or southeast component. This situation is common in summer, when the Azores anticyclone moves northward, and therefore weakens in the region. This is what is known as southern time.

The polar front also reaches here, when the Azores anticyclone is very far to the south and very far away towards the center of the ocean. This always means the arrival of more or less intense rains that fall on the opposite slope to that of the trade winds, since the winds have a N-NW component, but they also arrive with a NE and even SW component, which are what more precipitation they leave. Normally the Canary Islands are hit by the extremes of the troughs of the storms. Cold air masses lower temperatures but only moderately on the coast, and somewhat more markedly at altitude.

The combination of winds, the sea current and the centers of action makes the temperatures in the Canary Islands remarkably stable and less hot than what they would correspond to at their latitude. The highest temperatures are reached in August, although September has practically the same average. The coldest temperatures occur in January, closely followed by February. The thermal oscillation between the warmest and coldest months is below 10°C, between 17 and 25°C, except on the mountain peaks, where it can reach 13°C. The presence of the cold Canary Current means that heat waves reach the upper layers sooner than the lower ones. Thus, the typical negative altitudinal gradient that occurs with height in the Canary Islands is almost nullified.

The climate is conditioned by the topography. The existence of high mountains puts obstacles in the way of the trade winds. The barrier effect is enhanced in the mountains, and clouds and rain accumulate on the windward slopes, while the foehn effect is very active on the leeward side.

The rainfall presents a very clear pattern in which altitude is decisive. Lanzarote and Fuerteventura, low-lying islands, present very marked aridity features, with rainfall of less than 100 mm on the coast and 300 mm in the interior. In general, all the coasts of the islands receive rainfall below 300 mm. Precipitation increases progressively with altitude until reaching 1200 mm per year on the highest peaks. Only inside the ravines of Teide is there an area of lower rainfall in which 300 mm is not reached.

Vegetation

The Canary Islands are a true botanical paradise of Macaronesian species. Its climatic and topographic characteristics and insularity favor the appearance of endemism. In general, the Canarian vegetation is xeric in nature, however the position and hydrological conditions of the windward slopes allow the existence of even an ombrophyllous forest or rainforest. Thus altitude becomes a decisive element of the distribution of vegetation. In the Canary Islands we are going to distinguish five floors, the basal one dominated by a xeric scrub; the transition, dominated by a thermophilic juniper forest; the laurel forest floor; the floor of the pine forest; and the floor of the mountain scrub. In Lanzarote and Fuerteventura only the first two floors appear. The top floor only appears in Tenerife and La Palma. The constant winds make the plants adopt, in certain places, squat positions and tend towards horizontality. In addition to the floors, we must take into account the phenomena of recent colonization on the most modern volcanic flows. Finally, we must not forget the intense transformation of the anthropic biocenosis.

Basal floor

The basal floor develops between sea level and 200 meters of altitude. This difference depends on the position: leeward, higher, or windward, lower. It is characterized by the presence of a xeric thicket of species of the genus Euphorbia such as cardón and tabaiba. It is present on all the islands, but is dominant in Lanzarote and Fuerteventura. Halophilous species appear near the coast, such as sea lettuce, sea uvilla or immortelle. These species appear, particularly, in the salt flats. In the sandy areas of the eastern islands we find species adapted to this poor soil, with plants from the Chenolea family. On all the islands we find formations of tarajales and Canarian tamarix. This is the floor that has suffered the greatest anthropic impact, which has displaced most natural species. Thus we find large areas of gorse and commercial fruit trees. For a long time, grazing meadows for livestock were also extended, but the impact of the tourist economy has caused the abandonment of these areas and has allowed the appearance of opportunistic secondary species. It is the area most exploited by man since the last century, with banana crops and the development of tourism.

Transitional floor

The transitional floor extends from 200 to 500 or 1000 meters of altitude depending on the orientation. It is characterized by the presence of thermophilic species of arborescent nature such as the juniper, the wild olive, the peralillo, the mocán, the barbusano, the marmulán, the palm tree and the dragon tree. It is present in Gran Canaria, Tenerife, La Palma, La Gomera and El Hierro. It is not a floor that presents great uniformity. It is made up of more or less extensive isolated forests. The juniper forests stand out, located mainly on the west and southwest slopes. This floor has also suffered anthropic impact, since it coincides with the best cultivation areas (middlelands), being the place where most of the population centers were traditionally located.

Laurel forest floor

The laurisilva floor develops from 500 to 1200 meters on the northern and eastern slopes of the islands. It is an ombrophilous forest, which is made possible thanks to the many water conditions that we find, although the laurel is the most important. Mixing with the laurel forest appears heather and faya, which is a transitional form between this floor and that of the pine forest. It is considered that heather and faya appear as dominant species after the degradation of the laurel forest. It is present in Tenerife, Gran Canaria, La Gomera, La Palma and to a lesser extent in El Hierro.

Pine forest floor

The pine forest floor develops between 500 meters (leeward) or 1200 (windward) and reaches up to 2,000 meters high. Thus, it is more developed in the lee than in the windward, occupying the leeward areas in which the laurel forest is absent, due to low rainfall. Furthermore, they are found on slopes that have greater sunshine and a certain risk of frost. It is present in Tenerife, Gran Canaria, La Palma and El Hierro. The Canarian pine forests form the most extensive forest patches on the islands. The Canary Islands pine is the dominant species, and almost exclusive, since the undergrowth is very poor. The Canary Islands pine is characterized by its resistance to fire, an evolutionary adaptation in a volcanic archipelago.

Scrub floor

The mountain scrub floor develops above 2,000 meters of altitude. At such altitudes, and due to the peculiarities of the Canarian climate, the temperatures are low, the air dry, the wind strong and the sunshine intense. These are bad conditions for a tree layer to develop. The mountain scrub is a low, open formation with a creeping shape. We found this apartment only on the islands of Tenerife and La Palma. This floor is of fabulous floristic wealth. A notable part of the Canarian endemisms are found here, which is why the species that appear on La Palma are not the same, nor do they have the same importance as in Tenerife. On La Palma, codesares predominate, forming a compact thicket in which the brooms are confined in the rockiest areas. Retamón, pansy of the summits and canarian violet also appear. On the contrary, in Tenerife the broom predominates; while the lark is marginal, and the other species have a testimonial presence, although important in some sectors.