Correlation of Cave Levels and Planation Surfaces in the Pachmarhi Area, Madhya Pradesh: A Case for Base-Level Control

Abstract

Strong spatial juxtaposition of stream entrenchment and cave levels with planation surfaces in the Pachmarhi area reveals their mutual synchroneity during recurrent periods of epeirogenic uplift and stillstand that characterized the post-Deccan Trap (middle to late Cenozoic) erosion cycle.

Best correlation of cave levels with planation surfaces is observed in the downstream reaches of the drainage basins far removed from the drainage divides. Cave levels closely mimic the epeirogenically warped Upland planation surfaces indicating their base level control. Cave systems in the headwater regions are less well developed and appear to be controlled more by local tributaries. Both these observations indicate that trunk streams approach equilibrium sooner than their headwater reaches and hence cave levels cluster around the planation level in the downstream reaches where planation surfaces are also better developed. Periods of stillstand are therefore marked by intense cave development and periods of downcutting by stream entrenchment and drainage superposition.

Cave development and landform evolution in the Pachmarhi Area appear to be a non-cyclic but continuous process of recurrent epeirogeny and stillstand during the later part of the Cenozoic Era.