onlap

on +‎ lap

onlap (plural onlaps)

1. (geology) The phenomenon of successively younger rock strata extending progressively further across an erosion surface cut in older rocks.
   • 2001 December 14, Senthil Kumar et al., “Earthquake Recurrence and Rupture Dynamics of Himalayan Frontal Thrust, India”, in Science‎, volume 294, number 5550, DOI:10.1126/science.1066195, pages 2328-2331:

     Displacement on F3 was followed by continued accumulation and onlap of the fine-grained sands of unit 3 on the footwall and development of soil Qb2.

• overlap

onlap (third-person singular simple present onlaps, present participle onlapping, simple past and past participle onlapped)

1. (geology) To form an onlap.
   • 1998 March 6, Roger J. Phillips & Vicki L. Hansen, “Geological Evolution of Venus: Rises, Plains, Plumes, and Plateaus”, in Science‎, volume 279, number 5356, DOI:10.1126/science.279.5356.1492, pages 1492-1497:

     Elsewhere, many of the youngest volcanic plains units onlap tesserae at crustal plateau boundaries.

• offlap

• Plano, Polan, nopal, plano-