Dedegöl Dağı’ndaki Glasiyal Sirklerin Morfometrik Özellikleri
Türkiye’nin güneybatısında, Batı Toroslar dağ kuşağında yer alan Dedegöl Dağı’nda (2992 m) bulunan 30 glasiyal sirkin morfometrik özelliklerinin belirlenmesinin hedeflendiği bu çalışmada, sirklerin bakı, yükselti, eğim, boyut, şekil özelliklerinin analizi ve gelişim aşamalarına göre sınıflandırılması morfometrik parametreler çerçevesinde yapılmıştır. Sirkler temelde, buzul öncesi topografya, yükselti ve bakı etkisine, kısmen de lokal tektonik ve jeolojik yapıya bağlı olarak gelişmiş ve farklı özellik kazanmışlardır. Sirklerin dörtte üçüne yakın bölümü (73,3), güneş radyasyonuna daha az maruz kalan K, KD ve KB yönlerde gelişmiştir. Sirklerin ortalama taban yükseltisi 2543 m olup, kuzeye bakan yamaçlarda sirkler daha düşük kotlarda gelişme imkanı bulmuşlardır. Sirklerin morfometrik ölçümlerinden, ortalama 600 m uzunluk, 534 m genişlik ve 0,27 km² alan değerleri elde edilmiş, sirk uzunluğunun genişlikten biraz daha fazla olduğu görülmüştür. Buzul vadisi başlangıç noktasında, buzul vadisi yamaçlarında ve buzul vadisinden bağımsız noktalarda gelişim gösteren sirkler; sirk teknesi, basit, basamaklı ve birleşik sirk formunda olmak üzere farklı şekilsel özelliklere sahip olmuşlardır. Sahada iyi gelişmiş 11 sirk mevcutken, diğer 19 sirkin ya iyi gelişmemiş ya da orta derecede gelişmiş oldukları belirlenmiştir. Buzullaşmaların ilk başladığı dönemde, uygun lokalitede bulunan sirklerin pozitif geri besleme ile daha hızlı gelişim göstererek iyi gelişmiş olgun sirklere dönüştüğü değerlendirilmiştir.
Morphometric Characteristics of the Glacial Cirques on Mount Dedegöl
This study investigates the morphometric characteristics of 30 glacial cirques developed on Mount Dedegöl (2992 m) in the western Taurus mountain belt of southwestern Turkey. The elevation, slope, size, and shape characteristics of the cirques are analyzed and classifieded according to their developmental stages based on morphometric parameters. The development of cirques and their distinctive features are basically due to the pre-glacial topography, elevation, and aspect, and partly due to the local tectonic and geological structures. Nearly three-quarter of the cirques (73.3%) were developed in the N, NE, and NW aspects, which area less exposed to solar radiation. The average floor altitude of the cirques is 2543 m, and on the north-facing slopes, the cirques grew at lower elevations. From the morphometric measurements of the cirques, their mean length, width, and area are 600 m, 534 m, and 0.27 km², respectively, revealing that the lengths of most cirques are slightly larger than the corresponding widths. The cirques have distinctive features regarding forms, as they exist as troughs or simple, staircase, or compound cirques, and they are located at the head or slopes of the glacial valleys, or on an area isolated from the valley. We assessed and classified the cirques according to their developmental stages. The assessment results show that there are 11 well-developed cirques in the mountain and the remaining 19 are either moderately or poorly developed. The evaluation also shows that at the onset of the glaciations, the appropriately located cirques developed into mature cirques because of the facilitative environment.
This study investigates the morphometric characteristics of 30 glacial cirques on Mount Dedegöl (2992 m) in southwestern Turkey. The elevation, slope, size, and shape characteristics of the cirques are analyzed and classified according to their developmental stages based on morphometric parameters. Mount Dedegöl is situated in the west of Beysehir Lake in a sub-region called The Lakes District (Göller Yöresi) in the Mediterranean Basin. The mountain, as a part of the Western Taurus orogenic belt, extends from south to north. It approximately has a length of 12 km in the north––south direction and a width of 5––6 km in the east––west direction. The exposed bedrocks in the mountain massif are thick carbonate deposits of the Mesozoic era. The glacial erosional areas corresponding to the high sections of the mountain consist of completely massive limestones, mainly Dipoyraz Formation. Because of the glaciations that occurred during Quaternary cold periods, the higher sections of the Mount Dedegöl have evidences of erosional and depositional land forms of glacial topography. Glacier valleys over 7 km long, numerous cirques, and moraine deposits are evidences of the Pleistocene glaciation. The cirques are the most prominent glacial landform of all the six glaciated areas on Mount Dedegöl. They are usually located in the head of the glacier valley, and the glacier valleys begin with one or more cirques. Morphometric analyses of the cirques are carried out in detail in the study area, using modified forms of the methods created by Evans and Cox (1974; 1995) and Evans (2006), which have also been used by various researchers (e.g., Davis, 1999; Hughes, Gibbard, & Woodward, 2007; Marinescu, 2007; Mîndrescu, Evans, & Cox, 2010; Simoni, 2011). The morphometric parameters are based on a set of definitions formulated by Evans and Cox (1974; 1995). The values obtained by the morphometric measurements of the glacial cirques on Mount Dedegöl are mostly within certain limits and are close to the mean values. The morphometric properties of the cirques are discussed separately in terms of elevation, size, slope, and aspect. On Mount Dedegöl, 30 glacial cirques with distinct characteristics have been identified. Cirques were formed and developed in six sub-glaciated areas on the mountain: Sayacak, Kisbe Dere, Elma Dere, Karagöl, Muslu, and Kar Çukuru. The development and differentiation of the cirques are basically due to the pre-glacial topography, altitude, and aspect, and partly due to local tectonic and geological structures. Nearly three-quarter of the cirques (73.3%) were developed in the N, NE, and NW aspects, which area less exposed to solar radiation, thereby facilitating cirque growth. Only two cirques were developed in the SE and W aspects each because of unfavorable conditions, which include the local topographical conditions, ridges orientations, and pre-glacial valleys. The average floor altitude of the all cirques is 2543 m, and on the north-facing slopes, the cirques grew at lower elevations. Four cirques below 2400 m were developed in the north aspect. Cirques facing the SE and W directions were developed on relatively higher elevations. From the morphometric measurements of the cirques, their mean length, width, and area are 600 m, 534 m, and 0.27 km², respectively, revealing that the lengths of most cirques are slightly larger than the corresponding widths. We found that length exceeds width in 19 cirques, while width exceeds length in 9 cirques, and 2 cirques had equal lengths and widths. The cirques have an average area of 0.27 km², which is slightly below the ideal cirque size. The average circularity index for the cirques is 0.76, and13 cirques exceed 0.8. The circularity index is close to the upper limit value (0.8), indicating that the cirques are nearly circular. In the study area, the mean inclination angle of the cirques slopes is 28º, with the floor slope being 13º and the wall slope being 42º. These figures fall in the ideal range. The cirques have cave distinctive features regarding their forms, as they exist as troughs or simple, staircase, or compound cirques, and they are located at the head or slopes of the glacial valley or on an area isolated from the valley. We identified 10 simple cirques, 3 cirque troughs, 8 compound cirques, and 9 staircase cirques. Furthermore, 6 cirques are located at the head of the valleys, 21 on the slopes of the valleys and 3 in isolated areas irrelevant to the glacial valley. We evaluated and classified the cirques according to their developmental stages. The evaluations results show that there are 11 welldeveloped cirques on the mountain, and the remaining 19 are moderately or poorly developed. There is no direct correlation between the developmental stages of the cirques and their elevation. Several well-developed cirques were also grown at relatively low elevations, such as 2300––2400 m. The local factors which influenced the cirques development include prep-glacial topography, aspect, altitude, and geological structure. The evaluations also show that at the onset of the glaciations, the cirques located at the favorable locations developed into mature cirques by growing in a facilitative environment.
