Comments on “Monitoring soil erosion in Cappadocia region (Selime–Aksaray–Turkey)” by Yilmaz et al. (Environ Earth Sci 2012, 66:75–81)

Abstract

Yilmaz et al. (2012) presented a monitoring survey on soil erosion carried out around fairy chimneys of Cappadocia region of Turkey. They scanned the study area by geodetic robotic total station at five different times and calculated the volume differences in order to find out the total erosion during that given time interval. They finally analyzed the relationship between erosion and meteorological data and proposed that climatic conditions, especially rainfall, are an important eroding agent in the formation of this landscape. Whereas we welcome quantitative erosion surveys that are practically nonexistent in Turkey, the geological and geomorphological descriptions of the study area and scientific background contain vital mistakes that are totally unacceptable. Herein, some important ones are commented upon. Although the aim of Yilmaz et al.’s work is presented as ‘‘the study of the role of erosion of the surrounding soil in the formation of fairy chimneys’’, it is clear from their Figs. 1 and 4, where they show a photograph of the study area, that their work does not deal with any soil formation but rather is an outcrop of eroding ignimbrite. Therefore, the title of their work is misleading to say the least and do not represent their survey topic. On the other hand, even if we assume that the scanned area was covered by soil, which we insist is not the case, we are than entitled to question the use of such a method to measure the fairy chimneys erosion rates where no soil is involved during their formation. During the description of their study area the authors state, ‘‘the region was formed sixty billion years ago’’! It is common knowledge that the age of the Earth is 4.54 ± 0.05 billion years based on evidence from radiometric dating of meteorite material, which is similar to the ages of the oldest known terrestrial and lunar rocks (Dalrymple 2001). We believe that the authors and the reviewers did not see this obvious mistake. However, even if we assume that they meant ‘‘sixty million’’ instead of ‘‘sixty billion’’ they are still very far away from the calculated age of the rocks in the area. The reality is that the volcanism in Cappadocia situated in Central Anatolian Volcanic Province (CAVP), dates back to Late Miocene (around 10 My, My = Million years) to Holocene (Le Pennec et al. 2005; Aydar et al. 2012) (Fig. 1). The authors scientific inconsistencies do not end on the formation age of the study area as they claim that all rocks forming fairy chimneys were produced ‘‘by soft layers of lava and ash erupted from Erciyes, Hasan and Gullu volcanoes’’. Actually, these three stratovolcanoes are mainly Quaternary in age (around 2.5 My) (Aydar et al. 1995; Aydar and Gourgaud 1998; Kurkcuoglu et al. 1998; Şen et al. 2003) while the youngest ignimbrite layer (Kizilkaya Ignimbrite) that is known to form basin-wide mesas in the region is 5.2 My of age (Le Pennec et al. 1994; Aydar et al. 2012), hence was emplaced well before the eruption of these volcanoes. The stratigraphical framework of the region is very well established by several works where Ar–Ar and U–Pb zircon ages between 10 and 5.2 My are proposed for the formation of the ignimbrites that are susceptible to form fairy chimneys (Pasquare 1968; Innocenti et al. 1975; A. Ciner (&) Geological Engineering Department, Hacettepe University, Ankara, Turkey e-mail: aciner@hacettepe.edu.tr