Soft-sediment deformation structures in the Earth's oldest seismites

The Chaibasa Formation in Eastern India, which was deposited between 2100 and 1600 million years ago, shows deformations that must have formed when the sediments were not yet consolidated. Some of these deformation structures have never been described before. Here they are described, depicted and their origin is analysed. We show that they must be the result of shocks, which can only be explained satisfactorily as triggered by earthquakes. The layers containing these deformation structures are termed seismites. They are among the earliest records of earthquakes known in the Earth's history. (c) 2005 Elsevier B.V. All rights reserved.