Between the mouth of the Rio Tinto and that of the Guadalquivir the shore is lined by a series of sand-dunes, known as the Arenas Gordas.
Within the Carboniferous rocks, but due to the action of various agencies long after their deposition, are important ore formations; such are the Rio Tinto ores of Spain, the lead and zinc ores and some haematite of the Pennine and Mendip hills and other British localities, and many ore regions in the United States.
The view from the summit extends northward as far as the Grampians, with occasional glimpses of Ben Nevis; westward to Jura in the Atlantic; south-westward to Arran in the Firth of Clyde; southward to Tinto Hill, the Lowthers and Cairnsmore; and eastward to Edinburgh Castle and Arthur's Seat.
Free sulphur may also result from the decomposition of pyrites, as in pyritic shales and lignites, or from the alteration of galena: thus crystals of sulphur occur, with anglesite, in cavities in galena at Monteponi near Iglesias in Sardinia; whilst the pyrites of Rio Tinto in Spain sometimes yield sulphur on weathering.
One of the earliest and most exhaustive series of experiments was made on Rio Tinto ores at the John Brown works by John Hollway, with the aim of both smelting the ore and concentrating the matte in the same furnace, by the heat evolved through the oxidation of their sulphur and iron.
The sherry produced near Jerez de la Frontera, the copper of the Rio Tinto mines and the lead of Almeria are famous.