Insular geography of La Gomera
The oceanic island of La Gomera, situated some 350 km off the north-western African coast in the Canary Islands archipelago, with its area of 373 square kilometres is the second smallest of the islands after El Hierro (272 km²). Formed by successive volcanic eruptive cycles since 12 Ma BP, the current morphology of the island is the result of a prolonged and ongoing erosive activity, which has created numerous deep river gorges and carved out spectacular rock formations of the volcanic material.
Among the uncovered shapes we find the roques or rocks like Roque Agando, Ojila, San Pedro, Cano, etc., which are volcanic plugs revealed by differential erosion on softer materials. Table mountains such as La Fortaleza de Chipude, Montaña de Cherelepín, etc. are made by single prominent lava flows, whereas dykes are ancient linear eruptive structures crossing the accumulated lava flows like walls through long distances.
Nearly circular in shape, the central area of La Gomera is an elevated volcanic plateau from which a radial system of dry river gorges spreads down towards the coast. This high platform is found from 800 to 1300 metres above sea level and is commonly covered by the so-called sea of clouds stratocumulus blanket, which is dynamically formed when humid NE trade winds prevalent in the subtropics become banked up against the island’s highest mountain slopes.
This process gives rise to the so-called horizontal precipitation phenomenon which yields a large amount of moisture into the soil and creates an ambient of elevated atmospheric humidity all year round. The effect has favoured the survival of the most important mountain forest formation in the Canary Islands, the Garajonay National Park, which culminates in the highest point on the island at 1.487 metres.
As a result La Gomera is an extremely rugged island with huge height differences, in which the gorges are the most characteristic elements of landscape. The few flat areas are mostly found at the end of the gorges, where most of the human activity has been located. The coast of La Gomera is almost continuous cliff due to prolonged marine wave erosion, which has led to the gradual recession of the coastline and subsequent reduction of the island’s surface area. Hence the entire perimeter of the island is taken by large sea cliffs, only interrupted at the mouths of the most important gorges. These mouths have small beaches and bays which form the only convenient access points to La Gomera, the most important being the bay of San Sebastián with its principal port of the island.
The island shows all the bio-climatic layers of the Canary Islands owing to the contrast between the moist windward and the dry leeward sides, with the exception of the high mountain vegetation layer found only on higher islands of the archipelago. Insular topography is therefore the key factor which diversifies the climate on La Gomera and with it the characteristics and distribution of plant life.
As a result a series of vegetation layers can be distinguished on the island, deriving from variations in climatic parameters and atmospheric dynamics. A plain threefold division of vegetation on La Gomera separates i) the basal layer, between the coast and 400 metres above sea level, showing communities of dry scrub dominated by spurge species, ii) the transition layer, made up of shrubs such as rockroses and arboreal species such as date palm trees and junipers, and iii) the moist mountain layer, spreading in the north from about 500 metres upwards, and occupied by laurel woodlands and wax myrtle – tree heather forests.
Administratively the island of La Gomera is divided into six municipal districts, which are San Sebastián de La Gomera, Hermigua, Agulo, Vallehermoso, Alajeró and Valle Gran Rey. The current (2005) population of the island is nearly 22.000 inhabitants, who are mostly concentrated (80%) in the villages found on the valley floors. Apart from these areas there is a number of smaller settlements located on higher ground, among which Las Rosas, Chipude, El Cercado, Las Hayas, Alojera and Arure stand out.
Historically the Gomeran economy has been based solely on the primary sector, mainly on subsistence agriculture and, to a lesser extent, fishing. Until the 1970s La Gomera had not undergone any kind of economic diversification, but since then the economic base of the island has been transferred from the primary to the tertiary sector with the arrival of tourism and construction industry. The diversification of the economy has been favoured by the development of communications infrastructure, particularly by improvements in the road network and construction of new ports and an airport. Currently the relative weight of each economic sector is 3 % for the primary, 4 % for the secondary, 21 % for construction and 72 % for the tertiary sector.