Physical geography The park is named for the main geomorphological unit that covers the entire area, designated the Arrábida cordillera or massif, consisting of three subareas: • An area of small elevations around
Sesimbra, associated with the
Serra do Risco and
Serra da Arrábida, consisting of hilltops between Outão and Setúbal; • A zone between the
Serra de São Luís and the
Serra dos Gaiteiros; and • An area formed by the
Serras do Louro and
Serra de São Francisco. This group is oriented east-northeast to west-southwest, covering an area of about long and wide, and reaching at its highest altitude as a result of the Formosinho
anticline. Ribeiro (1935) indicates that the massif began to be formed with successive movements during the Tertiary era. Among the notable geomorphologic points-of-interest are the
Morro de Palmela, at , the
Montes de Azeitão, that include the
Serra do Louro, at ) and the
Serra de São Francisco ). Parallel to the
Serra do Louro, and more to the south, is the
Serra de Gaiteiros, at , to the southwest the
Serra de São Luís, at and to the southeast the
Serro do Viso at . There is also the Solitário Valley, between the coastal flanks of Arrábida and the Cabeços do Jaspe and Guincho, and the Vitória Valley, in the subplateau of the Serra do Risco. The coast stretching from
Sesimbra to Alpertuche is more varied and elevated than the one from Sesimbra to
Cape Espichel. The coast, generally elevated and abrupt, is at the
Alto do Píncaro, with rare and small beaches and coves, mostly accessible by boat. From Alpertuche to Outão the coast is less elevated resulting in more beaches, such as the bay of Portinho or Chã da Anixa, a small platform only metres above the sea. But, generally, the lands are inclined, mainly along the north and south, but predominately along the coast. Slopes in these areas of the Serra da Arrábida, Serra de Ares, Serra de Riscoa and Serra de São Luís exceed 30%, including the Rasca Valley, Comenda, Alto da Madalena Valley until Portela da Sardinha and areas along the north and south of the Serra de São Francisco and Serra de Louro. from Arrábida The waterways of Arrábida can be grouped into two principal types: • Waterways that only run during the winter months (following an irregular course whose flow increases substantially during these months); and • Perennial ravines that drain from the foothills throughout the year (with a longer, more stable course). The hydrology of the park is divided into two great basins: one to the northwest and north, and another to the south and east. Although the main waterways are in the east, between Setúbal, Palmela and the Picheleiros Valley, the ravine of Ajuda is the highest flowing waterway, and results from the confluence of the Ribeiras de Alcube e do Picheleiro, Ribeiras do Almelão and Ribeiras de Pomarinho. This basin includes the valleys of Picheleiro, Alcube and Ajuda, and the western and southern flanks of the Serra de São Luís, as well as the western flanks of the Nico and Viso, in addition to the Ribeira de Melra, Ribeira do Vale de Cavalo and Ribeira de Mareta. Other waterways, such as the Ribeira da Corva, tributary of the Ribeira de Livramento, or the Ribeira do Calhariz, tributary of the Rio Coina, obtain their maximum flow outside the park. Of all these waterways within the park, only the Ribeira da Ajuda maintains its flow throughout the year.
Climate Arrábida has a
Mediterranean climate with warm dry summers and mild wet winters. Its exposure to the Atlantic Ocean has a large influence over the temperature and the humidity felt throughout the year. The humid air masses that come from the Atlantic in the cooler months are confronted by the rugged mountains resulting in abundant precipitation in November and December. In the summer, some
upwelling occurs around
Cabo Espichel which decreases sea temperature and increases the frequency of
fogs, which are usually only present in the morning or late in the day. August is the warmest month with temperatures averaging between during the day and during the night. January is the coolest month with temperatures averaging between during the day and during the night. These temperatures depend on altitude and proximity to the sea.
Biome Flora Ulex densus occurs. '' branches within
Mediterranean forests, woodlands, and scrub The morphology of Arrábida allows a variety of microhabitats of distinct characteristics (
Mediterranean/
Atlantic), mixing species of evergreen, deciduous or semi-deciduous trees. Owing to the importance of the natural vegetation, that includes the last vestiges of varying Mediterranean vegetation, the area was included in a planning process early on, in order to save and preserve the ecosystems. There are three convergent floral elements: • Euro-Atlantic vegetation, with dominant exposures to the north, cooler humid or shaded areas; • Mediterranean vegetation, with dominant exposures in the south, warmer, dry or luminous areas; •
Macaronesian vegetation, occupying the accidented maritime lands and arribas. In the more eastern areas, the cliffs were populated with important species of Macaronesian flora, supporting nesting species of maritime and raptor birds protected by international convention.
Fauna In total there are 213 species of vertebrates: 8
amphibians, 16
reptiles, 154
birds, and 35
mammals.
Ecoregions and protected areas Arrábida concentrates a vast area of diverse vegetation, that includes 42 types and subtypes of habitats, 10 prioritized as important for conservation. • Atlantic coast maritime dune habitat, with herbaceous vegetation (
grey dunes); • Atlantic coast maritime dune habitat, with decalcified vegetation (
Calluno-Ulicetea); • Mediterranean coastal dune habitat, with forest of
stone pine (
Pinus pinea) or
maritime pine (
Pinus pinaster); • Mediterranean arborescent thickets of
bay laurel (
Laurus nobilis); • Rupicolous calcareous or basophilic grasslands of the Alysso-Sedion albi • Semi-natural dry meadows and scrublands on limestone (
Festuco-Brometalia); • Substep grasslands and Thero-Brachypodietea annuals; • Rocky slopes with chasmophytic vegetation and limestone slabs • Temperate alluvial forests of
common alder (
Alnus glutinosa) and
European ash (
Fraxinus excelsior) • Low formations of spurge (
Euphorbiaceae), that include
Euphorbia pedroi The complexity and diversity of marine habitats present in the waters of Arrábida have contributed to it being a hotspot of biodiversity, with 1400 registered species occupying the space. ==Popular culture==