Abstract: Extremely abundant biogenic trace foosils exist within the sediments of all kinds from Late Precambrian to Presentday.ln respect of stratigraphy and sedi-mentology, it is quite meaningful to study them.In addition, trace fossils could. 1.Indicate compactness of sedimentary rocks, 2.Provide some clues to the drrectinns of ancient water currents during sedimentation and, 3.Be used to determine the top and bottom surfaces of rock formation.In this paper, implications of trace fossils are discussed with stress on their application to stratigraphy and sedrmentigraphy and sedimentology.