Activities in the natural environment->Mountain range Orihuela->Geology

To look for the origins of the Sierra de Orihuela we must go back to the Triassic period, 240 million years ago. At that time, in the southern part of the peninsula, there was a shallow sea at the bottom of which the materials that would later give rise to the rocks of the sierra were sedimented.

About 70 million years ago, the thrust of the African plate in its northward movement caused this sea to dry up and the materials to sink under higher pressure and temperature, compacting until they became metamorphic rocks. Finally, for about 8 million years, the "collision" of the African plate with the European plate has been producing the folds and uplifts of the land that have given rise to the Sierra de Orihuela and in general to the relief of the region.   

The Sierra de Orihuela is one of the few places in the province of Alicante where there has been metal mining in the past. The most important is related to iron. At various points on the southern slope of the mountain range, and in the Barranco de las Minas located on the northern slope, there are mines and mining prospects for this metal. Most date from the 19th century, although there is evidence of mining activity since prehistoric times. These mines are made up of a simple shaft or a horizontal gallery, although there are also some more complex ones. The most important minerals are oligisto or hematite and goethite, although siderite, pyrite and ocher have also been described. Some silicates associated with these mineralizations are asbestos or asbestos (crocidolite) or chalcedony. Also noteworthy is the cinnabar mine, for the extraction of mercury, known as the Santa Matilde mine.

This mine, located on the Oriolet hill next to the San Antón neighborhood, was opened in 1863 and remained active for two or three years. In addition, in the Sierra de Orihuela, in the district of La Aparecida, there are copper mineralizations at levels of Triassic quartzites. As a curiosity, there are references to the presence of native copper, silver and gold (which some authors say gives the name to the city, "Aurariola." These mineralizations continue in the Sierra del Puerto, already in the Region of Murcia.

Finally, due to the carbonate nature of the rocks, there is abundant calcite. There are also references to various gypsum mines, and alabaster quarries. The metallic mineralizations of the Sierra de Orihuela (iron, cinnabar and copper) were formed in one of the main “metallogenetic” periods of the Betic Cordillera: the Triassic. Its origin may be linked to volcanic activity. Orihuela mineralizations are associated with metabasite outcrops, which are magmatic rocks.

At first glance the Sierra de Orihuela may appear to be a uniform rock mass, but in reality there are five main sets of rocks:

Carbonates · Limestone and dolomitic composition, gray in color and compact in appearance. They make up most of the Sierra de Orihuela.

Phyllites and quartzites · They come from the metamorphism of clays and sandstones respectively. Violet, bluish gray or greenish in color. They are found on the southern slopes of the sierra and in the Baronesa ravine.

Chalcoesquistas · They are the product of marl metamorphism. They have yellowish or light brown tones. Abundant on the path that goes up to the Cruz de la Muela.

Metabasites · They are igneous rocks (gabros-diorites) poor in quartz, that is, basic from the geochemical point of view, made up of plagioclase and pyroxene crystals with some amphiboles (hornblende and actinolite), which have undergone metamorphism. Hence the name assigned to this type of rock: meta- (metamorphism) and -basite (basic rock). The Cerro del Oriolet is an old quarry of metabasites, which supplied stone for the manufacture of cobblestones.

Brechas · Sedimentary rocks generated by the accumulation of fragments of other rocks that come from the erosion of the mountains. They form the alluvial fans that surround the mountain range.

Alcalde Vicente Escudero, 2
03300 Orihuela
Contact Numbers
Palacio del Agua: 966 076 100 Extensiones 3400-3401
Oficinas Clequali Orihuela: 687 666 665
CDM Playas de Orihuela: 603 749 826

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