The question asks about a specific term introduced by Crickmay to supplement or modify the concept of 'peneplain', originally proposed by Davis. Crickmay disagreed with aspects of Davis's theory and proposed a related but distinct term.

Crickmay's Panplane Term

Geomorphologist Albert Banner Crickmay, while discussing landscape evolution and erosion surfaces, proposed the term Panplane. He felt the concept of a peneplain, as defined by William Morris Davis, did not fully encompass certain landform characteristics he observed.

• Davis's Peneplain: A nearly flat surface of low relief, representing the final stage of the cycle of erosion.
• Crickmay's Supplement: Crickmay introduced Panplane, suggesting a surface formed by the coalescence of pediplains, which he considered a more accurate representation in certain contexts than the traditional peneplain. He proposed this term to refine the understanding of extensive, low-relief surfaces.

Therefore, Crickmay supplemented the concept of peneplain with the term Panplane.