Abstract
Abundant specimens of trace fossils have been found from several exposures of the Jurrasic and the Cretaceous sediments in the northeastern area of the Kanto Mountains. They belong to Phycosiphon incertum and Scalarituba isp. Size distributions of these ichnospecies are different in each locality and horizon. These trace fossils are found in silty part of the alternating sandstone and mudstone beds or in the single mudstone layer. Judging from the sedimentary feature and the mode of the fossil occurrence, these trace fossils are considered to be pascichnia formed in turbidite. They are presumed to reflect frequent sedimentation, because they belong to a simple palaeoich-nocoenosis composed of only two ichnospecies formed by opportunisitic burrowers.
