Dryas mafi tsufa

Mafi tsufa Dryas wani yanki ne na yanki na biostratigraphic wanda yayi daidai da wani yanayi mai sanyin yanayi ba zato ba tsammani, ko stadial, wanda ya faru a lokacin ja da baya na glacial na ƙarshe .   Lokacin lokacin da Layer ya dace ba shi da ma'anar da ba daidai ba kuma ya bambanta tsakanin yankuna,  amma yawanci yana farawa a 18.5-17 shekaru dubu ( ka ) kafin yanzu (BP) kuma ya ƙare 15-14 ka BP .      Kamar yadda yake tare da Matasa da Tsofaffi abubuwan da suka faru na Dryas, layin stratigraphic yana alama da yawan pollen da sauran ragowar Dryas octopetala, nau'in nuna alama wanda ke mamaye yankuna na arctic-alpine. Ƙarewar Tsohon Dryas yana da alamar balaguron isotope na isotope na oxygen, wanda aka lura a wurare da yawa a cikin Alps waɗanda suka dace da wannan tazarar lokaci. 

A cikin Alps, Tsohon Dryas ya dace da filin Gschnitz na Würm glaciation. An fara bayyana kalmar ne musamman don bayanan ƙasa a yankin Scandinavia, amma an yi amfani da ita don ƙirar kankara a yankuna a duk faɗin duniya, da kuma komawa ga lokacin lokaci da kansa da kuma juyawa na wucin gadi na koma baya. Rasmussen, Sune O.; Bigler, Matthias; Blockley, Simon P.; Blunier, Thomas; Buchardt, Susanne L.; Clausen, Henrik B.; Cvijanovic, Ivana; Dahl-Jensen, Dorthe; Johnsen, Sigfus J.; Fischer, Hubertus; Gkinis, Vasileios; Guillevic, Myriam; Hoek, Wim Z.; Lowe, J. John; Pedro, Joel B.; Popp, Trevor; Seierstad, Inger K.; Steffensen, Jørgen Peder; Svensson, Anders M.; Vallelonga, Paul; Vinther, Bo M.; Walker, Mike J.C.; Wheatley, Joe J.; Winstrup, Mai (December 2014). "A Stratigraphic Framework for Abrupt Climatic Changes during the Last Glacial Period Based on Three Synchronized Greenland Ice-core Records: Refining and Extending the INTIMATE Event Stratigraphy". Quaternary Science Reviews. 106. Amsterdam: Elsevier: 14–28. Bibcode:2014QSRv..106...14R. doi:10.1016/j.quascirev.2014.09.007. hdl:2160/30436.

A cikin Yankin Iberian, kankara na Pyrenees, Sierra Nevada, Tsakiyar Tsakiya, da Dutsen Arewa maso Yamma, wanda kusan ya ɓace gaba ɗaya ta 17,500 BP, ya fara ci gaba da ci gaba. Tsakanin 16,800 da 16,500 BP, waɗannan kankara sun ci gaba ba zato ba tsammani zuwa kwarin tsaunuka kuma sun ajiye moraines kusa da moraines da aka kafa a lokacin Last Glacial Maximum. Wadannan kankara sun fara juyawa tsakanin ci gaba da koma baya har zuwa ci gaba na ƙarshe a 15,500 BP. Shekaru dubu bayan haka, biyo bayan janyewar kankara gaba ɗaya, an sake mayar da waɗannan kankara na alpine zuwa circus.

 Tsire-tsire 
A lokacin Tsohon Dryas, Turai ba ta da itace kuma tana kama da tundra na Arctic, amma ya bushe kuma ya fi tsami fiye da tundra ta zamani. Ya ƙunshi shrubs da tsire-tsire masu tsire-shuke kamar su:

 Poaceae, ciyawa
 Artemisia
 Betula nana, karamin birch
 Salix retusa, karamin willow
 Dryas octopetala

 Dabbobi 
Dabbobi sun fi yawa Arctic amma a lokacin Glacial Maximum, nau'ikan yanayi masu zafi sun janye zuwa mafaka kuma sun fara sake cika Turai a cikin Tsohon Dryas.

Bear mai launin ruwan kasa, Ursus arctos, yana daga cikin na farko da ya isa arewa. Nazarin kwayoyin halitta ya nuna cewa bears masu launin ruwan kasa na Arewacin Turai sun fito ne daga wani mafaka a cikin Carpathians na Moldova. Sauran 'yan gudun hijira sun kasance a Italiya, Spain da Girka.

Bears ba za su koma arewa ba sai dai don neman abinci. Dole ne tundra ya riga ya cika da jama'a. Wataƙila jinsunan da mutane suka farauta a Tafkin Neuchâtel a Switzerland a ƙarshen lokacin sun kasance a lokacin. Ga wasu dabbobi da ke wurin:

 Gavia arctica, mai baƙar fata
 Podiceps nigricollis, mai baƙar fata
 Cygnus cygnus, wanda ke da ƙanƙara
 Aquila chrysaetos, gaggafa ta zinariya
Tsuntsayen da ke sama galibi na teku ne. Dole ne su ci abinci a cikin ruwan da ke cikin arewa wanda aka fara saki.

 Lota Lota, burbot
 Thymallus thymallus, mai launin toka
 Rutilus rutilus, zakara
 Zabura, trout
 Salvelinus alpinus, karusa
Ƙananan dabbobi masu shayarwa na jerin abinci sun zauna a cikin bargo mai laushi na tundra:

Cricetidae

 Discrotonyx torquatus, lemming mai wuyan gaske
 Microtus oeconomus, tsutsa
 Microtus arvalis, tsuntsu na yau da kullun
 Chionmys nivalis, tsuntsu mai dusar ƙanƙara

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