The leveling of a landscape by erosion.
- ‘Indications of planation near the Inner SDR might either indicate that this unit formed partly under subaerial conditions (subaerial seafloor spreading) or that an uplift episode occurred after its emplacement.’
- ‘Nevertheless, hints of a pronounced planation surface which caps the Forest of Dean at a height of about 200 m has been reported by Maddy.’
- ‘Anglo-American geomorphologists tend to the view that pediments are the result of either lateral planation by ephemeral, migrating streams issuing from bordering mountains, or sheet-flood erosion.’
- ‘These profiles show evidence for planation at the top of the Outer Plains close to the Inner SDR.’
- ‘Instead, a widespread planation surface of presumed mid-Miocene age is recognized across western Britain, western Wales, Ireland and potentially northern France.’
- ‘Until recently, our understanding of the evolution of megaphylls largely stemmed from Zimmermann's telome theory describing the sequence of overtopping, planation and webbing leading to appearance of the laminated leaf blade.’
- ‘The Lofoten Margin Flows does not show any planation surfaces on top and its seismic character is very similar to normal oceanic crust.’
- ‘We interpret this unit as a result of submarine emplacement based on its rough top reflection and the lack of planation surfaces.’
Late 19th century: from plane + -ation.