Ƙarshen (geomorphology)

Ƙarshen, kamar yadda masana kimiyyar ƙasa na Quaternary, masu nazarin teku, da masu ilimin yanayi na zamani suka yi amfani da shi shine lokacin lokacin lokacin sake zagayowar glacial lokacin da akwai sauyawa mai sauri daga cikakken yanayin glacial zuwa cikakken yanayin Interglacial. Ga Lokacin Quaternary, ana ƙidaya ƙarewa ta amfani da lambobi na Roman daga ƙarshen baya-bayan nan kamar "I" kuma tare da ƙaruwa da ƙima, misali "II", "III", da sauransu, zuwa baya. Ƙarshen I, wanda aka fi sani da Ƙarshen Glacial na Ƙarshe, shine ƙarshen matakin isotope na Marine 2; Ƙarshen II shine ƙarshen Mataki na Isotope na Marina 6; Ƙarshen III shine ƙarshen Matakin Isotope Na Marine 8; Ƙarshen IV shine ƙarshen Matakan Isotope Mataki na Marine 10, da sauransu.

A lokacin Quaternary, yanayin duniya ya sami tsarin maimaitawa na ci gaban kankara da lalacewa. Tsawon zagayen Late Quaternary ya bambanta tsakanin shekaru 80,000 da 120,000, tare da matsakaicin maimaitawa na kimanin shekaru 100,000. Tsarin glacial na Late Quaternary ya kasance asymmetric yana da dogon lokacin sanyaya wanda aka nuna shi ta hanyar haɓaka kankara zuwa matsakaicin girma. Tsawon lokacin sanyaya ya biyo bayan ɗan gajeren lokacin dumi. A wannan lokacin zafi, wanda ake kira ƙare, [1] manyan kankara na Arewacin Hemisphere sun narke; matakin teku ya tashi kusan mita 120 (390 ; kuma yanayin interglacial ya fito a fadin duniya a cikin 'yan dubban shekaru. Idan aka kawo karshen zagaye na ƙarshe na kankara, koma baya na kankara na nahiyar a Arewacin Hemisphere ya fara kimanin shekaru 20,000 da suka gabata. Kimanin shekaru 7,000 da suka gabata, wani karamin kankara a Tsibirin Baffin shine duk abin da ya rage na babban Laurentide Ice Sheet wanda ya taɓa rufe arewacin Arewacin Amurka. A Antarctica, ƙarshen ƙarshe ya fara kimanin shekaru 18,000 da suka gabata kuma an kai yanayin interglacial kusa da shekaru 11,000 da suka wuce.[2][3]