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TURKIYE JEOLOJI BULTENI-GEOLOGICAL BULLETIN OF TURKEY, no.4, pp.665-699, 2017 (ESCI)
Towards the mid-nineteenth century, the unconsolidated deposits, which are mostly occupy quite large areas particularly in North Eurasia and North America, have become the main argument among the geoscientists. Although the term 'Quaternary' has been suggested as a time unit in that century, this period had often been shown in the maps under the headings of 'diluvium-alluvium' or 'old/new alluvium'. While the origins of these Quaternary aged units had been discussed under hot debate, these units have felt their importance from the beginning. However, during the mapping studies, the Neogene and Quaternary units have not been elaborated for many years on geological maps and are generally seen to be roughly mapped only as age units. A large part of the settlements around the world are located in plain areas that covered by the Quaternary deposits because of the attraction of geographical conditions, such as transportation suitability and interaction with water resources. Due to the rapidly increasing human population and urbanization, there is a growing need for detailed mapping of these units beyond their characterization as only 'alluvium'. From the beginning of the twentieth century, attempts have been made to map the Quaternary units, particularly on the European scale, but these attempts have not resulted because of the Second World War. Although the lithology was considered firstly in the early Quaternary geological maps, it is observed that the ages and depositional environments of the units are taken into account in the world generally. In addition to this criterion, grain size, grain and mineral composition, coastal and glacial lines, and engineering characteristics are also considered in the geological mapping of Quaternary in some countries. In Turkey, the mapping of Quaternary plains, where the settlements developed rapidly on, has become a necessity firstly for engineering purposes, especially after the 1999 earthquakes. At the same time, in terms of their great scientific value for climate and active tectonics researches, their importance also increases the need for mapping of these units. In this study, the evaluation of current approaches in the preparation of Quaternary geological maps and encountered major problems have been made on the basis of examples from various parts of the world and from Turkey.