Santa Clara is the smallest island of the Juan Fernandez Islands and has an area of about. It is surrounded on the south side by a reef. This volcanic islet is related to a group of three islands. Located southwest of Robinson Crusoe Island, it has a mainly flat surface, with a maximum altitude of at Johow Hill. Based on its geomorphological characteristics and the composition of its lavas, it is postulated to be the earliest volcanic center which led to the emergence of Robinson Crusoe Island, and is, therefore, of greater antiquity - 5.8 million years. Santa Clara includes volcanic rocks and several small beaches, including some white sand beaches. A short distance from the western extremity of Santa Clara Island, there is a small rocky islet, and, at the tip south of the same islet, there is a sandbarcomposed of various rocks which break the water. Coming from the north, the island of Santa Clara has the appearance of a cliff or escarpment; but approaching from the south, shows an eroded quirky aspect of conical mounds and strangely cut rocks. Waters surrounding the island have a rocky bottom, with strong currents. Access by boat to the island is dangerous, especially in stormy weather, because the strong sea breaks on all sides.
Climate
Being low-lying in elevation, Santa Clara catches relatively little rainfall. The amount of rainfall also depends on the El Niño-Southern Oscillation. The climate is subtropical, strongly influenced by fluctuations in the general northward flow of the cold sub-Antarctic Humboldt ocean current and the southeast trade winds, which create a high-winter and low-summer rainfall pattern and a stable temperature environment. Temperatures range throughout the year from to, with an annual mean of.
Flora and fauna
Santa Clara is generally desolate and barren, but in its eastern slope there are some trees, and in the northwest tip a periodical stream of water runs along the gorge, which reaches the sea. The low vegetation has been eroded in the past by herds of goats up on the rocks. The native flora is characterized by low fire tolerance and poor adaptation to herbivore resistance. Feral rabbits are the greatest threat because they exert devastating effects on the island’s habitats. The majority of the original vegetation on the island has been replaced by shrubs and grasses. The vegetation is a miniature mosaic of matorral, barren rock, various size trees, and shrubs mixed with ferns and perennial herbs. Nearly all of Santa Clara is abundant in the introduced Rubus ulmifolius, Aristotelia chilensis, Ugni molinae, Lantana camara and Lonicera japonica. Some have the potential to be serious pests, having fleshy fruits that are bird dispersed, in addition to weeds such as Danthonia collina, Stipa laevissima and Piptochaetium bicolor. There are no permanent sources of fresh water on the island. Vertebrates inhabiting the islet include birds, some endangered, which make their nests on or visit the island.
