page_title: Porto Santo Island
section_title: Physical geography
hierarchical_section_title: Porto Santo Island / Geography / Physical geography
caption_attribution_description: English: Basalt columns on Porto Santo Island, Madeira
context_page_description: Porto Santo Island is a Portuguese island 43 kilometres northeast of Madeira Island in the North Atlantic Ocean; it is the northernmost and easternmost island of the archipelago of Madeira, located in the Atlantic Ocean west of Europe and Africa.
context_section_description: The island is characterized by two areas: the accidented northeast (mountainous, with rocky ledges and cliffs), and a coastal plain in the southwest (that includes a nine-kilometre long white sand beach, giving the island an advantage over neighbouring Madeira). The mountainous northeast part of the island, consists of two geomorphological structures that includes: an area of peaks, Pico do Castelo (437 meters), Pico da Juliana (447 meters), Pico da Gandaia (499 meters) and Pico do Facho (517 meters); and between the eastern coast and this area, a series of minor peaks, Pico do Maçarico (285 meters), Pico do Concelho (324 meters) and Pico Branco (450 meters). The southwest part of the island, although relatively flat, includes a series of elevations 100 meters in height or greater, such as Pico Ana Fereira (283 meters), Pico do Espigão (270 meters) and the Cabeço do Zimbralinho (183 meters). The slope of the western part of the island slopes from 150 meters to the south coast reaching the sandy beaches of Porto Santo. A third system, in the west-northwest, that includes Cabeço da Bárbara Gomes (227 meters) and Cabeço das Canelinhas (176 meters) is distinct from the areas identified. The island is encircled by an oceanic platform between 20 and 37 km², with a minimum depth of 8 meters (Baixa do Noroeste), and limited by the flanks of a large submarine volcano.
  The island's submarine activity occurred during the Miocene epoch, producing basaltic eruptions that persisted to the Quaternary period. There were three phases of distinct volcanism, followed by periods of calm associated with sedimentation:
  1st Phase - associated with basaltic lava, pyroclastic flows, trachyte domes that were to form Pico do Concelho, Pico do Facho, Pico do Juliana and the Ponta da Calheta. This period was followed by a period of marine fossil accumulation, concentrated in the northeast of the island to about 300 meters altitude (around Pico do Juliana, Pico de Ana Ferreira and Ribeira do Moledo);
  2nd Phase - this was a period of fissural volcanism that cut across and metamorphosed the older formations, occurring in the early Pliocene period;
  3rd Phase - was an intrusive phase, resulting in a number of faults and dikes that cut across the Calcareous fossils. Likely occurring in the Pliocene, it was followed by deposits of layers of detritic and calcareous sediments, that included brownish-red alluvial layers, along the island's flanks and beach.
caption: A formation of Mugearite columns in the coastal region
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