Radiocarbon Dating: Alluvial Fan/Debris Cone Evolution and Hazards

Abstract

Radiocarbon dating has contributed considerably to the understanding of alluvial fan and debris cone evolution, as well as their hazard and risk potential. This development mirrors the contributions made in investigations of other depositional environments since invention of the technique in the 1950s (Cook and van der Plicht 2007; Jull 2007). Radiocarbon dating involves measuring the amount of the radioisotope 14C preserved in fossil organic materials and using the rate of radioactive decay to calculate the age for a given sample. The application of radiocarbon dating to secure the development and evolution of alluvial fans requires the deposition and preservation of organic materials within the sedimentary stratigraphy. The dating technique has been used widely to reconstruct the development of alluvial fans in temperate to sub-arctic regions where environmental conditions are conducive to the presence and preservation of organic materials. The age limit to the application of radiocarbon dating ranges from approximately 45,000 years to typically several hundred years. Thus the technique is relevant for constraining the age of alluvial fans since the middle of the last cold stage, Marine Isotope Stage (MIS) 2 (45–11.5 ka) through the current interglacial (11.5–0 ka), the Holocene.