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Abstract: We report the first discovery of outcrop-scale, fine-grained sediment waves in the left-side muddy overbank deposits relative to the down-current direction of the adjacent channel deposits in the lower Halang Formation turbidite system in a late Miocene back-arc basin, West Java. The present outcrop examples are characterized by an average wavelength of 10.7m and an average wave height of 0.13m, and the aspect ratio is similar to that of modern large-scale, fine-grained sediment waves. The dimension and asymmetry of waveforms decrease in the down-current direction in association with the increase in wave steepness. In particular, aggradation and up-current migrating of waveforms are commonly observed in the proximal part of overbank deposits. Furthermore, the stoss-side deposits locally contain thicker and coarser sandstone and coarse siltstone beds (beds up to 5cm thick) than those of the lee-side deposits. The basal part of individual waveforms does not contain any sandy bedform and/or irregularity as a precursor for developing asymmetrical waveforms from fine-grained turbidity currents. These spatial variations in geometry and component deposits of the waveforms are interpreted to have been formed under antidune or cyclic-step and standing-wave conditions from the proximal to distal overbank environments, respectively. The present outcrop-scale examples can fill the gap in dimension and formative processes between laboratory-scale bedforms and modern large-scale, fine-grained sediment waves for elucidating scale-independent processes, which are responsible for the development of fine-grained waveforms in a deep-water environment. [ABSTRACT FROM AUTHOR]