Tsarin rushewa

Tsarin ƙasa, ko **sake zagayowar [[Zaizayar Kasa|rushewa]]**, samfurin da ya dace wanda ke bayyana ci gaban taimako a cikin shimfidar wurare. Misali ya fara ne tare da rushewar da ke biyo bayan hauhawar ƙasa sama da matakin tushe kuma ya ƙare, idan yanayin ya ba da izini, a cikin samar da peneplain. Yankunan da ke nuna shaidar fiye da sau ɗaya na rushewa ana kiransu "polycyclical". Tsarin rushewa da wasu ra'ayoyin da ke tattare da shi, duk da shahararsu, sun kasance batun zargi da yawa.

## Bayyanawa
William Morris Davis, wanda ya samo asali na samfurin, ya raba shi zuwa *matasan* wanda sauyawa ya yi kama da rayuwar ɗan adam watau *matasan* *matasan* Matsala, Matasa Matashi Matasa da Tsohon Matasa. Misali ya fara ne da wani uplifted sate na wuri mai faɗi. Sa'an nan Davis ya bayyana wani mataki na matasa inda yankan kogi ko rushewar tsaye shine babban tsari da ke tsara wuri mai faɗi. A lokacin tsayin matashi, bambance-bambance tsakanin tsaunuka da ƙasan kwari suna ƙaruwa da sauri. Mataki na matasa yana biye da wani mataki na *balaga* wanda bambance-bambance na tsawo tsakanin ƙasan kwari da tsaunuka suna da girma. A cikin matakin *balaga*, raguwar gangara ya zama abin da ya fi muhimmanci yayin da rushewar gefen ya mamaye,  kuma tsaunuka sun rasa tsawo da sauri fiye da koguna, yadda ya kamata ya rage taimako. A cikin sabon mataki, rushewar ta yi aiki na dogon lokaci har da wuri mai faɗi, duk da tsayinsa na asali, an rage shi zuwa *ƙasa mai juyawa*. Wannan wuri mai sauƙi ana kiransa peneplain kuma yana iya ƙunsar tsawo da ke tsaye daga matakin gaba ɗaya. Za'a iya ɗaga peneplain, wanda ke fara zagaye na biyu na rushewa.

daji ya yarda cewa cikakken sake zagayowar lamari ne na musamman kuma cewa haɓakawa na farko ba lallai ba ne ko kuma ya biyo bayan dogon lokaci na kwanciyar hankali. Koyaya, kamar yadda Walther Penck ya nuna, Davis da mabiyansa galibi suna amfani da saurin haɓaka da kwanciyar hankali don bayyana shimfidar wurare. Wannan yana nufin cewa samfurin, kamar yadda yawancin suka fahimta, yana ɗaukar saurin tashi da kuma tasowa. Wani halayyar samfurin shine cewa gangaren suna samo asali ne ta hanyar raguwa, tare da gangaren da suka fi tsayi da aka yi amfani da su ta hanyar rushewa wanda ke samar da gangaren masu sauƙi. [A] Rashin ƙarfi na samfurin shine cewa galibi yana da ka'idoji da ƙididdiga a cikin yanayi kuma ba ya la'akari da rikitarwa na motsi na tectonic ko Canjin yanayi. Yanayin matakai na sama ma ba shi da kyau ta hanyar samfurin. Misali a cikin asalinsa an yi niyya ne don bayyana ci gaban taimako a cikin shimfidar wurare masu matsakaici wanda lalacewa ta hanyar ruwa mai gudana ana ɗaukarsa muhimmiyar mahimmanci. Duk da haka, an tsawaita sake zagayowar rushewa, tare da gyare-gyare, cikin busasshiyar, rabin busasshi, Savannah, selva, glacial, bakin teku, karst da yankunan periglacial. Rubuta a cikin 1950 Louis C. Peltier ya yi iƙirarin sake zagayowar lalacewa a cikin yanayin teku da yanayin yanayi shine kawai wanda ba a bayyana shi dalla-dalla ba.

## Tarihi

### Tarihi
Akwai wasu ra'ayoyi game da rushewar cyclical a cikin duniyar Graeco-Roman sannan a cikin duniyar Islama da Turai a lokacin Tsakiyar Tsakiya. Koyaya tasirin William Morris Davis, mahaliccin sake zagayowar tsarin rushewa, sun kasance masu binciken Amurka na ƙarni na 19. Ƙarshen Yaƙin basasar Amurka (1861-1865) ya haifar da ci gaba da binciken yammacin Amurka. Masu bincike uku, John Wesley Powell, Clarence Edward Dutton da Grove Karl Gilbert, sun rubuta game da ilimin ƙasa da ilimin ƙasa a cikin shimfidar wurare da suka haɗu. Daga waɗannan ayyukan ne Davis ya ranta ra'ayoyi da yawa da aka yi amfani da su don gina samfurin.

An yi jayayya cewa ra'ayoyi daga fannin ilmin halitta sun rinjayi Davis, musamman tunanin Neo-Lamarckian wanda yake a yanzu a ƙarshen karni na 19 na Amurka. An yi tunanin cewa Davis ya sami wasu daga cikin wannan tasirin Neo-Lamarckian daga malaminsa, Nathaniel Shaler . Sauran ra'ayoyin halittu waɗanda zasu iya tsara sake zagayowar lalacewa sune na orthogenesis da recapitulation dukansu suna da alaƙa da Neo-Lamarckianism. ka'idar juyin halitta ta Darwin ƙaramar tasiri ce dangane da Neo-Lamarckism. Za'a iya nuna tasirin waɗannan ra'ayoyin a cikin amfani da samfurin na manufar "juyin halitta" maimakon "canji", wanda ke nuna hanyar da za'a iya hangowa game da yanayin wuri da canjin ƙasa. An yi jayayya cewa "Davis da gangan ya yi amfani da Darwinism ga shimfidar wuri".

### Godiya da zargi na farko
Davis ta yi tunanin sake zagayowar tsarin rushewa a cikin shekarun 1880 yayin da take nazarin Appalachians a Pennsylvania da Virginia. Davis ya rubuta ka'idar Cycle of erosion dalla-dalla a karo na farko a shekara ta 1889. Ya fi bunkasa a shekara ta 1900 ya sami yabo mai yawa, amma ba a taɓa yarda da shi a duniya ba. An danganta sha'awar farko da ƙarfin sake zagayowar lalacewa ga dalilai daban-daban. Na farko, samfurin ya ba da tsari don nazarin yankuna da lokutan a tarihin Duniya inda rushewa shine babban tsari. Na biyu, samfurin ya dace da babban tunanin juyin halitta wanda ya fito a karni na 19 tare da ka'idar juyin halitta ta Darwin. A ƙarshe, ana iya danganta wasu shahararrun ga salon rubuce-rubucen Davis. Misali ya sami karbuwa mafi girma a cikin shekarun 1900-39 lokacin da aka buga karatu da yawa game da jerin lokuta masu banƙyama bisa ga samfurin. A cikin waɗannan binciken yawanci an gano zagaye biyu zuwa biyar na rushewa. Hanyar yin jerin lokuta tare da sake zagayowar lalacewa ya rasa shahara daga shekarun 1930 zuwa gaba. Wataƙila wannan ya kasance saboda hanyar ba ta samar da wani fahimta ba. Yawancin masu ilimin ƙasa sun fara nazarin hanyoyin da ke faruwa a yanzu kuma ba a baya ba kamar yadda aka yi tare da sake zagayowar tsarin rushewa. Wadannan masu ilimin ƙasa ba da daɗewa ba sun fahimci wasu abubuwan da suka lura sun saba da tsarin Davis. Sauran masu ilimin ƙasa sun juya daga sake zagayowar lalacewa don yin aiki a maimakon haka a kan yanayin yanayi ko ilimin ƙasa.

Misali ya bazu da sauri. A cikin 1901 Hans Reusch yana amfani da shi don bayyana tsaunin da ke kan kudancin Norway. Davis Walter Wråk ya yi tasiri sosai don nazarin taimakon tsaunukan Scandinavia na arewa, yana kwatanta da sauran abubuwa da Borsu surface. B. Willis da abokan aiki ne suka buga binciken farko na yanayin kasar Sin ta amfani da samfurin a cikin 1907.  An yada ra'ayin sake zagayowar lalacewa tsakanin daliban koleji da jami'a tare da jerin litattafan da aka buga a cikin shekarun 1890 da 1900. A cewar Sheldon Judson har zuwa rahotanni na Yaƙin Duniya na Biyu game da ilimin ƙasa na yanki sun haɗa da taƙaitaccen ambaton sake zagayowar lalacewa da kuma peneplanization.

Duk da yake an fara karɓar samfurin a tsakanin malaman Anglo-Saxon,  a cikin nahiyar Turai ya sadu da wasu juriya tare da malaman Jamus Albrecht da Walther Penck, Siegfried Passarge da Alfred Hettner da ke tsaye a matsayin abokan adawar farko ga samfurin.  Duk da kokarin Davis, wanda ya hada da fassara aikinsa zuwa Jamusanci, kasancewa farfesa mai ziyara a Berlin da kuma yawon shakatawa da yawa a Turai, sake zagayowar lalacewa bai taba samun tushe mai ƙarfi a Jamus ba. Walther Penck ya samo asali ne daga wani madadin samfurin tare da nasa ka'idoji. Mahaifinsa, Albrecht ne ya buga ra'ayoyin Walther bayan mutuwarsa a 1924. A cikin samfurin Walther, an tsara taimako a matsayin aikin denudation / uplift rate. Davis, abokiyar mahaifin Walther,  ya soki sabon samfurin Walther. Binciken Davis game da littafin Walther Penck na biyu a kan batun ya bar ra'ayi mara kyau game da ra'ayoyin Penck tsakanin ma'aikata daga baya. Wannan shi ne saboda Davis bai fahimci ba kuma ya fassara ɓangarorin takarda ba, saboda haka Davis ba isasshen mai sukar aikin Penck ba ne.

A Faransa Albert de Lapparent ne ya fara yada ka'idar lalacewa. Gabaɗaya an haɗa karɓar ta a Faransa tare da Emile Haug yana ba da ɗan hankali ruwa Paul Vidal de La Blache yana karɓar ta ba tare da ajiya ba. Sauran sanannun masana ilimin ƙasa na Faransa waɗanda ra'ayoyin Davis suka rinjayi game da sake zagayowar rushewa sune Emmanuel de Martonne da Henri Baulig .  Geomorphology a Faransa ya ci gaba zuwa makarantu biyu, daya ya dogara ne akan masu ilimin ƙasa waɗanda suka karɓi tunanin Davisian kuma wani ya dogara ne da ilimin injiniya tare da haɗin zuwa hydraulics da hakar ma'adinai.

### Babban zargi (1945-1974)

A cikin 1960 masanin ilimin ƙasa Sheldon Judson ya lura cewa masu ilimin ƙasa na Amurka sun fi watsi da manufar kuma sun koma nazarin shimfidar wuri da yanayin ƙasa daga tsari da ra'ayi na kididdiga. Eiju Yatsu ya yi imanin, duk da haka, cewa duk da niyyar da yawancin masana kimiyyar ƙasa suka yi na watsar da ra'ayoyin Davisian bayan Yaƙin Duniya na Biyu, mutane da yawa sun ƙare sun koma gare su tare da wasu gyare-gyare.

Lester Charles King ne ya gabatar da wata ka'idar sake zagayowar a cikin shekarun 1960. Duk da yake ra'ayoyin Sarki sun kasance ƙoƙari na karyata sake zagayowar Davis na lalacewa su kansu sun kasance na yanayin cyclical kuma sun ba da gudummawa ga gabatar da raƙuman zargi a cikin shekarun 1960 a kan duka samfuransa da Davis. Wannan zargi an kira shi "Davis bashing" ta Cliff Ollier kuma ya zama wa Ollier ba'a game da ka'idojin cyclical a cikin ilimin ƙasa ba tare da an gabatar da wani samfurin madadin ba. Tun da yake ra'ayoyin Davis suna lalacewa wasu fannoni na bincike, kamar na yanayin yanayi, an kai musu hari ta hanyar haɗin da suka yi da shi.

An soki ra'ayoyin lokaci, tsawo, gangaren da juyin halitta a fili sake zagayowar rushewa. Bugu da ƙari an yi tambaya game da ingancin wasu ra'ayoyin da ke da alaƙa da sake zagayowar lalacewa ciki har da matakin rafi, raguwar gangara, matakin tushe na D da kuma mafi yawan duk abin da ke cikin peneplains.

Rubuce-rubuce a cikin 1971 masanin ilimin ƙasa Ronald Flemal ya taƙaita halin da ake ciki kamar haka:

### Matsayi na zamani
Despite considerable criticism the cycle of erosion model has remained part of the science of geomorphology. The model or theory has never been proved wrong, but neither has it been proven. The inherent difficulties of the model have instead made geomorphological research to advance along other lines. In contrast to its disputed status in geomorphology, the cycle of erosion model is a common approach used to establish denudation chronologies, and is thus an important concept in the science of historical geology. While acknowledging its shortcomings modern geomorphologists Andrew Goudie and Karna Lidmar-Bergström have praised it for its elegance and pedagogical value respectively. Writing in 2007 Anthony Orme evaluates that:

: *"an cire kayan juyin halitta, Davisian Cycle of Erosion yana da cancanta a matsayin aikin fassara, kuma hakika har yanzu yana da cancantar a matsayin memba na ƙarshe a cikin abubuwan da za su iya faruwa na lokaci don ci gaban duniya. "*

## Bayani

## Manazarta