The exokarstic soil record of past environmental changes: regional expressions.

We intend to promote using microfacies analysis how the Quaternary deposits filling karstic cavities that are part of galleries connected by vertical chimneys to the outside surface soils provide an original view on the reactivity of limestone landscapes to short-term environmental changes. Our purpose is illustrated by the early to middle Pleistocene sequences from the Sierra de Atapuerca (Burgos, Spain) and the latePleistocene/Holocene sequence of Song Terus (Gunung Sewu hills, Java Island). The micromorphological study and complementary analytical data have allowed subdividing the pedo-sedimentary facies into six types in terms of accumulation and pedogenic processes: (F1) Weakly pedogenised sedimentary facies; (F2) Weakly pedogenised pedo-sedimentary facies; (F3) Excremental pedogenic facies; (F4) Dark organic-rich facies; (F5) Calcitic facies; (F6) Firing facies. They are shown to reflect the range of short-term events that might have severely degraded the soils forming on the limestone landscapes along the course of the Quaternary period in response to various initiating factors, i.e. exceptional abrupt climate changes, wildfires, volcanic eruptions or cosmic impacts. The rapid fossilisation and the negligible anthropogenic bias explain the excellent preservation of the pedo-sedimentary records in the subsurface karstic galleries. Further study should help to better understand the effects of these ecological crisis on human and animal communities that were occupying in the past the limestone landscapes.