Evolution of Holocene alluvial landscapes in the northeastern Songshan Region, Central China: Chronology, models and socio-economic impact

Abstract

A recent suggestion of the existence of an enormous ancient waterbody in Central China had been associated with the intensifying water management that led to the rise of early states. However, the evolution of regional alluvial landscapes remains unclear. Through intensive geoarchaeological surveys and careful field examination of typical sedimentary sequences, we reconstructed Late Pleistocene-Holocene landscapes in the northeastern Songshan Region and identified three distinctive models of landscape evolution. In the loess hills and tablelands areas, rivers were characterized by the large-scale alluvial aggradation during the terminal Late Pleistocene. Following a slight river incision during the Early Holocene, a pronounced alluvial aggradation resumed throughout the Middle Holocene. This gave way to another episode of river downcutting during the Late Holocene. The platform-type plains area witnessed a similar process of landscape evolution. However, the amplitude of the Early Holocene river-incision was smaller, whilst the large-scale Middle Holocene aggradation filled up the valleys, which also led to the formation of buried terraces. The eastern plains area was marked by continuous alluvial-lacustrine aggradation from the Late Pleistocene onwards. Many lakes, marshes and wetlands were formed during the Middle Holocene river aggradation. These waterbodies were separated by the high-elevation landforms, creating a mosaic-like aquatic landscape. The Late Pleistocene-Holocene landscape supported mixed farming of rice and millets from the Neolithic to Bronze Age. After 4000 BP, with another event of river incision, the wetlands shrank, and the extensive area of drylands emerged in the east plains. This change coincided with the emergence of large-scale urban centers in the region.