Arid Diagonal
TheArid Diagonal(Spanish:diagonal árida/arreica) is a contiguous zone ofarid and semi-arid climatethat traversesSouth Americafrom coastalPeruin the Northwest to ArgentinePatagoniain the Southeast including large swathes ofBoliviaandChile.[1]The Arid Diagonal encompasses a number of deserts, for example:Sechura,Atacama,Monteand thePatagonian Desert.
The Arid Diagonal acts to isolate thetemperate and subtropical forests of Chile and southern Argentinafrom other forests of South America.[2]Together with theQuaternary glaciationsin the SouthernAndes,the diagonal has controlled the distribution of vegetation throughout Chile andArgentina.[3]
The concept of a South American Arid Diagonal was first coined by French geographerEmmanuel de Martonnein his 1935 workProblème des régions arides Sud-Américaines.[4]However, few works dealing with the Arid Diagonal mention this foundational text.[4]The original Arid Diagonal of de Martonne went fromAntofagastain northern Chile to the northern coast of ArgentinePatagonia.[4]however, other authors like Margarita González Loyarte (1995) later extended it to the coast of northern Peru.[4]
Cause and origin[edit]
The northern portion of the Arid Diagonal is a result of the blocking of thetrade windsby the barrier formed by theCentral Andesand theSouth Pacific High.[5]To the south in thewesterlies,therain shadowthat the Southern Andes casts over eastern Patagonia similarly blocks moisture.[1]South ofMendoza(32°53' S), the driest parts of the diagonal move away from the Andes as the mountains lose height, causing some humidity to penetrate; thus, at more southern latitudes the driest parts of the diagonal lie on theAtlanticcoast of Patagonia.[1]
The Arid Diagonal has existed since theNeogene.[3]The origin of the aridity of northern part of the diagonal is linked to two geologic events: a) the rise of the Andes — an event that led to the permanent block of both thewestward flowof moisture along the tropics, and the eastward flow of moisture in Patagonia[6]and b) the permanent intrusion of cold Antarctic waters (theHumboldt Current) along South America's west coast.[5]Together with theQuaternary glaciationsin the Southern Andes, the diagonal controls the distribution of the vegetation types over Chile and Argentina.[3]
References[edit]
- ^abcBruniard, Enrique D. (1982). "La diagonal árida Argentina: un límite climático real".Revista Geográfica(in Spanish): 5–20.
- ^Villagrán, Carolina;Hinojosa, Luis Felipe (1997). "Historia de los bosques del sur de Sudamérica, II: Análisis fitogeográfico".Revista Chilena de Historia Natural(in Spanish).70:241–267.
- ^abcVillagrán, Carolina;Hinojosa, Luis Felipe (2005). "Esquema biogeográfico de Chile". In Llorente Bousquests, Jorge; Morrone, Juan J. (eds.).Regionalización Biogeográfica en Iberoámeríca y tópicos afines(in Spanish). Mexico: Ediciones de la Universidad Nacional Autónoma de México, Jiménez Editores.
- ^abcdAbraham, Elena María; Rodríguez, María Daniela; Rubio, María Clara; Guida-Johnson, Bárbara; Gomez, Laura; Rubio, Cecilia (2020-01-08). "Disentangling the concept of" South American Arid Diagonal "".Journal of Arid Environments.175:104089.Bibcode:2020JArEn.175j4089A.doi:10.1016/j.jaridenv.2019.104089.S2CID213655544.
- ^abArmesto, Juan J.; Arrollo, Mary T.K.; Hinojosa, Luis F. (2007). "The Mediterranean Environment of Central Chile". InVeblen, Thomas T.;Young, Kenneth R.; Orme, Anthony R. (eds.).Physical Geography of South America.Oxford University Press. pp. 184–199.
- ^Folguera, Andrés; Encinas, Alfonso; Echaurren, Andrés; Gianni, Guido; Orts, Darío; Valencia, Víctor; Carrasco, Gabriel (2018). "Constraints on the Neogene growth of the central Patagonian Andes at the latitude of the Chile triple junction (45–47°S) using U/Pb geochronology insynorogenic strata".Tectonophysics.744:134–154.Bibcode:2018Tectp.744..134F.doi:10.1016/j.tecto.2018.06.011.hdl:11336/88399.S2CID135214581.