Abstract
The Echigo Plain facing the Sea of Japan is a typical coastal plain covered by coastal sand dunes. Depositional systems along the lower Agano River have been clarified by the facies analysis of borehole datasets and by four newly obtained sediment cores. The upper parts of the alluvium in this area have been formed as a delta system with strong influence of the Agano River. This system is in contrast with a barrier-lagoon system, the subsiding area along the Shinano River in the Echigo Plain. Therefore, it is evident that the alluvium of the Echigo Plain has been formed by the progradation of two different depositional systems, a delta system under the influence of the Agano River and barrier-lagoon system under the impact of the Shinano River.
