River terraces as a response to climatic forcing: Formation processes, sedimentary characteristics and sites for human occupation

Climate impact on the fluvial processes led to morphological and sedimentological differentiation of a terrace. This diversity in the fluvial environment determined how people could adapt to the river. Although the climatic impact on development and initiation of river terraces seems to be well accepted, a number of pertinent questions disturb this simplicity. For instance: The exact terrace development within a climate cycle is still under debate. Different kinds of terraces and their sedimentary successions may originate either from aggradation, incision or lateral migration. Is there a typical sedimentary succession below terraces? What is the genetic origin of each sedimentary layer? What are the relative ages of those layers and erosion phases within a climate driven erosion -aggradation cycle? The variability in staircase preservation in relation to climatic cyclicity is analysed in three scenarios. Specific scenarios depend essentially on the preservation of the fluvial deposits dating from the warm periods. Finally, a preliminary inventory is presented of the most favourable sites for human occupation in fluvial valleys as derived from a random selection of archaeological findings. Generally, human occupation in that morphological position seems to be linked with, at least temporarily, dry conditions. Climatic conditions do not seem to play the major role. The termination of a settlement may have been due to increased risks of flooding, apart from other than natural fluvio-environmental reasons. (C) 2014 Elsevier Ltd and INQUA. All rights reserved.