A yau zamuyi magana ne game da wani nau'i na tsarin ilimin ƙasa wanda aka samo shi daga sauƙƙarwar kankara. Game da shi garwa. Wannan sunan ya fito ne daga Irish "droim" ko "drim" kuma yana nufin "dutsen tsauni". Samuwarsa ta fito ne daga kayan taimako na ƙanƙan da kai kuma ba komai bane illa ƙaramin tuddai tare da gangaren santsi wanda ke kama da kifin whale mai kwance. Ana haifar da su daga samfurin kankara a cikin kwatankwacin motsawar kankara a lokacin ƙanƙarar iska.
A cikin wannan labarin za mu gaya muku duk halaye, horo da son sani na drumlin.
Babban fasali
Muna magana ne game da wani irin karamin tudun ƙasa wanda ya ƙunshi tsaunuka masu santsi. Gangaren masu santsi suna da wannan layin tun daga kankarar kankara da lokutan narkewa suna haifar da yashewa ta abrasion. Siffar drumlin ita ce ta kifin kifi kirin kirin kwai kuma ana ƙirƙira shi ta shugabanci na motsa jiki galibi wanda kankara ke ɗauke dashi yayin shekarun kankara.
Saboda ana samun ganga dab da ajiyar moraine, ana ɗaukar su azaman tsari daga moraine wanda ake samarwa a ƙasan glacier. Moraines saiti ne na abubuwan ƙyalƙyali masu ƙyalƙyali waɗanda suka taru a gefen tartsatsin kankara. Suna iya bayyana a keɓe amma an fi samun su cikin ƙungiyoyi kamar su yana faruwa a yankin Patagonia na Chile. Kuma shine cewa saitin abubuwan da suke samarda moraines suna motsawa zuwa cikin kankara tare da iska mai rinjaye. Mun san cewa kankara ma tana da nata motsi dangane da gangare da lokacin kankara.
Kirkirar da tambarin
Bari mu ga menene tsari wanda ake samar da drumlin. Mun san cewa su wani yanki ne na shimfidar wuri wanda aka sanya shi ta aikin kankara. Akwai muhawara da yawa game da asalin tambarin, kodayake ra'ayoyin da abin ya shafa sune wadannan:
- Kayan ne da aka samar ta hanyar ambaliyar ruwa a ƙarƙashin ƙanƙarar duwatsu. Wannan alluvium yana iya jigilar abubuwa da yawa a cikin lokaci guda kuma yana tarawa a tashoshin ƙaramin kankara. Waɗannan tashoshi sune inda ruwan yake gudana, wanda yake daskarewa, amma daga ƙananan ɓangaren kuma yana ci gaba a cikin yanayin ruwa. Mun san cewa kankarar ta makale a laka amma ba a daskarewa gaba daya. Partasan ƙanƙan kankara wanda ke juyawa da ƙarancin ƙasa da ƙasa yawanci a cikin yanayin ruwa ne kuma shine ke da alhakin motsa kankara.
- An kafa ta da babban kankara mai ƙanƙan da kankara wanda a hankali yake karawa saman duniya. Idan muka koma ga karcewar saman duniya muna magana ne akan wani nau'in zaizayawa wanda ake kira abrasion. Abrasion tsari ne da ake samarwa ta hanyar jan ɗigo da nauyin kowannensu. Wato idan kankara ta ratsa ta saman wani fili, takan samar da abrasion saboda tsarinta kuma kasar tana laushi kuma tana da taushi mai laushi.
Samuwar ganga tana da alaƙa da nau'in kayan da ke yin waɗannan tsaunuka. Kuma shi ne cewa yawan tasirin dasunan yana da muhimmiyar rawa a cikin aikin haɓaka. Idan abubuwan da ke ƙarƙashin kankara da aka tara ta cikin lokutan dusar ƙanƙara suna iya yiwuwa, yana da wuya a ja shi tunda zai tace.
Kayan Drumlin
Bari mu ga menene ainihin kayan aikin da aka yi tambarin da shi. Abu na farko shine sanin abin da ya ƙunsa da lakar ƙanƙara. Wannan laka mai ƙarancin ruwa an san ta da sunan har. Cakuda ne na yumbu, yashi da tsakuwa waɗanda suke da gefuna masu kusurwa kuma wani lokacin suna da bulolin duwatsu. Gilashin yana jan waɗannan kayan kuma ya ajiye su a ƙasan. Ta wannan hanyar, ya kasance kayan da za'a samu ta jigila mai ƙarancin haske.
Wasu lokuta laka na iya samar da tambarin da motsawar ruwa ya haifar ta rafin da ke yawo a karkashin kankara. Kamar yadda muka ambata a baya, a ƙarƙashin ruwan kankara akwai ruɓin ruwa a cikin yanayin ruwa kamar kogi. A cikin 'yan lokuta kalilan kankara ta daskare gaba ɗaya. Musamman a lokacin narkewa, bangaren da ya juye zuwa yanayin ruwa shine mafi sauri shine ɓangaren cikin kankara. A wannan yanayin, lokacin da ake kirkirar drumlin ta Kogunan da ke zagayawa ƙarƙashin ƙanƙarar sun haɗa da tsakuwa tsakuwa.
Sigogin tarawa
Tun daga shekarun kankara na ƙarshe, kimanin shekaru 18.000 da suka gabata, kankara ta ja baya, ta bayyana abubuwan da aka gada tun daga lokacin da ya mamaye lokacin shekarun kankara na ƙarshe. Wannan shine, ta hanyar lokacin narkewa da raguwar farfajiyar da ta lulluɓe shi, yana bayyana sauƙi tare da yin samfurin kankara.
Adadin ruwan dusar kankara da aka sani da har zuwa lokacin sune keɓaɓɓun abubuwan da aka sanya su kai tsaye ta kankara. Waɗannan kayan ba su da rarrabewa kuma gutsurensu suna nuna faɗuwa sakamakon sauyawa da gogayya da ƙasa. Moraines tsari ne wanda aka hada shi da kwayoyi wadanda suka taru a gefen glaciers. Idan kankara ta sauka an adana wani zaren gwangwani mai fasalin wayo wanda ake kira basal moraine. Da zarar ya ci gaba da ja da baya, gaban zai iya daidaitawa kuma ya samar da halin ɓacin rai.
Moananan moraines yawanci sun fi dacewa da ƙyallen kwari. Su ke kula da jigilar duk abubuwan da ke ƙasa tare da iyakarta kuma an ajiye su tare da tsaunuka masu tsayi. Lokacin da aka haɗu da halayen moraines tare da haɗuwa da kwari biyu, ana yin moraine na tsakiya.
Aƙarshe, da zarar an ajiye abubuwan ƙyallen a wajen ƙanƙarar kuma iska da aikin wasu masanan ilimin ƙasa su kwashe su, sai a kafa dunƙulen. Akwai wasu tsarin tsarin geomorphological wanda ya samo asali ne daga sauƙƙarwar ƙyalƙyali kuma waɗanda suka haɗu da tarkace madaidaiciya kuma suna kame, terraces kame, da masu siye.
Ina fatan cewa tare da wannan bayanin zaku iya ƙarin koyo game da tambarin da halayensa.