Lithostratigraphy and Alluviation History of Quaternary Deposits of Southern Part Of Gangetic Plain, Uttar Pradesh

The Quaternary sediments of a southern part of the Gangetic Plain in parts of Allahabad, Banda, Fatehpur, Hamirpur, Pratapgarh and Raebareli districts of Uttar Pradesh have been classified into the Banda Older Alluvium (BOA), the Varanasi Older Alluvium (YOA) and the Newer Alluvium, each representing different eycles of sedimentation in basins of different configuration during different periods. The Banda Older Alluvium resting over the Bundelkhand Gneissic Complex or the Vindhyan Supergroup, represents the first cycle of Quaternary sedimentation which has been sub-divided into the basal Variegated clays and an upper Chitrakoot Formation. These sediments had their provenance in the Peninsular terrain. The Varanasi Older Alluvium constituting the second cycle of sedimentation comprises polycyclic sequence of sand, silt and clay with or without calcrete bands. Its sediments di ffers in mineralogical assemblage from that of Banda Older Alluvium and have been derived from Extra Peninsular region. The Newer Alluvium, the third cycle of sedimentation, has been sub-divided into Terrace Alluvium and Recent Alluvium confined within the palaeobanks of the rivers.

The evidences in favour of neotectonic movements recorded in the area are displacement of beds, deformational structures in Newer Alluvium, unusual straightening and abrupt changes in the river courses and sudden widening of flood plains or entrenchment of the rivers. An attempt has been made to work out the alluviation history of the Quaternary sediments of the area on the basis of available palaeontological data and some close lithological similarities.