An overstep is a geological form that has a deposition of a stratum across inclined, progressively older rocks.[1]

The Indira Gandhi National Open University syllabus definition is: "The term overstep is used to describe the relationship of beds in an unconformable sequence where the younger series rests upon progressively older members of the underlying series."[2]

An onlap is a more general term than overstep, in which the younger beds overlap onto successively older beds.

References

  1. ↑ Alistair F. Pitty Structure and Relief 1985 Page 28 "An overstep is a geological term describing the deposition of a stratum across inclined, progressively older rocks, as seen on both flanks of the Market Weighton axis (figure 9). In South East England, the Lower Greensand is another very ..."
  2. ↑ Indira Gandhi National Open University (School of Sciences), (Undated). BGYCT-131 - Physical And Structural Geology, Block 3 - Structural Geology, Unit 12 - Joints And Unconformities. egyankosh.ac.in. Archived.


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