Sierra Nevada, Spain
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Geology (main)
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Sierra Nevada range from La Calahorra, showing agriculture, forest and snow cover. @ C.Michael Hogan
The Sierra Nevada is a significant mountain range in Andalucia, in southern Spain, whose highest point is 3478 meters. This mountain range represents the tallest landform in all of southwestern Europe, even exceeding the Pyrenees. There is a vast variation in climate within the Sierra Nevada, since snow covers the higher elevations for most of the year, while hot temperatures prevail at the lower elevations, particularly in summer. As a result of these climatic differentials as well as the Mediterranean (Mediterranean Sea) influences on the southern slopes, there is enormous biodiversity within the Sierra Nevada; this species richness is further amplified by the considerable soil differences within the mountain range.
While human history in the Sierra Nevada dates back at least as early as the early Holocene, there is also a well documented written history beginning in the Roman era, with some of the more western reaches of the Roman Empire consisting of villages along the southern flanks of the Sierra Nevada in the era 50 BC to 150 AD. The Phoenicians, and later the Carthaginians, had a presence in the Sierra Nevada that even predated the Romans.
Contents
Geology
The Sierra Nevada exhibits a central core comprised of a dome consisting chiefly of mica schist; this core extends for a west-southwest to east-northeast line of about one hundred kilometers, and manifests a topography of somewhat smooth contours at the higher elevations. Younger Triassic limestone and sandstone form the middle and lower slopes, which zone is deeply incised by the generally north or south flowing rivers that endure year around, due to the copious snowmelt.
The upper montane zones have been considerably influenced by glacial activity during the most recent Ice Age; this glacial scraping has created numerous residual moraines, one of which is 2.5 kilometers in length. There was likely a small disjunctive ice sheet that covered much of the high Sierra Nevada during most of the most recent ice age, perhaps enduring as recently as fifteen to twenty thousand years before present.
Ecology
287px Iberian conifer forests occupy most of the Sierra Nevada. Source: WWF The major ecoregion comprising the Sierra Nevada range is the Iberian conifer forests; a less prominent low elevation ecoregion occupying chiefly lower slopes is the Iberian sclerophyllous and semi-deciduous forests, which is particularly evident in the southeastern Sierra Nevada. However, the most important way to dissect the habitats within the Sierra Nevada by using altitudinal characteristics; there are five chief ecological zones within the, Sierra Nevada, as viewed by elevational factors:
- Alpine
- Pre-alpine
- Hedgehog scrub
- Mediterranean montane
- Mediterranean
Alpine zone
The highest zone of the Sierra Nevada ranges above 2600 meters and consists chiefly of herbaceous perennials that can tolerate snow and ice cover that persists the majority of the year. Approximately 200 distinct plant species are found in this alpine zone, around 40 of which are endemic. Among the most abundant endemics are: Ranunculus acetosellifolius, Meum nevadense, Linearia glacialis, Eryngium glaciale and Saxifraga nevadensis. Around twenty of the flora taxa found here are common to Morocco's Atlas Mountains, and about a dozen species of the alpine zone are shared by other mountain ranges of southern Spain; moreover, approximately 70 of the plant taxa found in the alpine zone are also found in the Alps (e.g. Draba azoides, Gentiana verna, Vitaliana primuliflora, Erigeron alpinus and Saxifraga oppositifolia.
Pre-alpine zone
Elevations of this zone may be construed to lie between 2300 and 2600 meters in altitude. Niches seen occupied by spiny shrubs in the Hedgehog scrub at lower elevations, are supplanted here by dwarf juniper taxa, Juniperis communis subsp. nana and J. subina subsp. humilis.
Hedgehog scrub zone
While some of this zone, lying between 1700 to 2300 meters in elevation, is forested with pine species, the greater fraction is covered with a low scrub, many of which component species manifest a characteristic dome geometry. These shrub species are generally sparsely distributed on the stony slopes; many of these taxa bristle with sharp spines and comprise a set of taxa that are common to similar height montane zones in North Africa and other parts of the European Mediterranean. Characteristic species of this zone are Bupleurum spinosum, Erincea amthyllus, Astralagus granatensis, and Vella spinosa, the last of which assumes a xeromorphic form in this zone.
Mediterranean-montane zone
This ecological zone spans elevations of 1200 to 1700 meters. In the late Holocene this realm was covered in majority by native oak woodlands, most of which have now been destroyed (Habitat destruction) by agricultural land conversion; however, there are some notable extant stands of these oak forests in such places as the east side of Laroles Canyon about two kilometers north of the village of Laroles. In any case, many of the understory plants characteristic of such oak woodlands are still present in this zone, including: Stachys lusitanica, Phlomis criinita, Lavandula lanata, Salvia lavandafolia, Geum heterocarpum, Digitalis obscura, Helleborus foetidus and Paeonia coriacea.
Mediterranean zone
Intensively cropped areas on Sierra Nevada south slopes, Laroles Canyon, about 1200 meters elevation. @ C.Michael Hogan This heavily disturbed zone lies below elevation 1200 meters. While there are remnants of oak forests in steep or stony soils, most of the primordial tree cover is removed, with replacement by cultivated olives, oranges and almonds along with introduced chestnut trees. Characteristic native shrubs found in this zone are Genista umbellata, Helichrysum stoechas and Lygos sphaerocarpa; moreover, the limited distribution plant Anthyllis vulneria subsp. argyrophylla occurs only in southern Spain, including the Sierra Nevada. At the upper extent of this zone are found many deciduous spiny thickets comprised of such taxa as Berberis hispanica, Rosa micrantha, and Ulex parviflorus subsp. funkii.
Hydrology
The northern slopes, being more steep, generally offer more rapidly flowing streams than the southern flanks of the Sierra Nevada. Snowmelt keeps many of the streams as perennial features, even though most flow rates are modest. A number of river diversions exist particularly on the southern slopes, where agriculture has been nurtured for at least the last three millennia. Many of these diversions occur at altitudes as high as 1500 meters to supply water to almond, olive and other crops. Results of these diversions include degradation (Habitat destruction) of considerable riparian habitat.
The principal river draining the northern slopes is the Rio Genil, which ultimately discharges to the Rio Guadalquivir. The origin of the name Genil derives from the river's Roman name Singilis, belying the early presence on the northern slopes by the Romans. The southern flanks are drained by a series of relatively narrow river valleys such as the Rio Laroles.
Ancient history
Bowl from Los Millares. Source: José-Manuel Benito Álvarez
Prehistory of the region includes not only Neanderthal presence but also very early Homo sapiens who left elaborate cave paintings at such sites as Cuevas de la Pietra circa 30,000 years before present, situated not far from the western verge of the Sierra Nevada. An elaborate chalcolithic age city was discovered at Los Silillos, also somewhat west of the Sierra Nevada, with an areal extent of around 180,000 square meters. At the eastern end of the Sierra Nevada is an even more well known archaeological site of Los Millares, which dates to at least as early as the late fourth millenium BC as a chalcolithic site, whose culture influenced the entire region.
The written history of the region, including the minting of coins, shows some of the earliest sophisticated settlements to have been of Punic origin. Coinage records indicate the majority of ancient coin mintage in the region to have come from Roman times, and to have occurred on lower flank southern slope locations. Interestingly, the coin designs show evidence of Punic and local Iberian tribe influence. indicating Roman concessions to earlier cultural traditions. It is also notable that the third largest Roman city in the entire Empire lay only slightly west of the Sierra Nevada at Italica.
References
- Charles Anthon. 1850. A system of ancient and mediæval geography books.google.com 269 pages
- Aurelio del Castillo y Antonio del Castillo. Ed. Penibética. 2003. Sierra Nevada: Guía de Montaña. ISBN 84-932022-3-1
- A.T.Fear. 1996. Rome and Baetica: urbanization in southern Spain c. 50 BC - AD 150. Oxford University Press England. 292 pages
- Wes Gibbons and Teresa Moreno. 2002. The geology of Spain. Geological Society of London books.google.com 649 pages
- C.Michael Hogan. 2007. Los Silillos. Modern Antiquarian. Ed.Julian Cope
- Oleg Polunin and B.E.Smythies. 1987. Flowers of Southwest Europe. Oxford University Press, England. 480 pages
