Some Non-Diastrophic Structures in the Lower Siwalik of the Haldwani-Tanakpur Area, Uttar Pradesh

Some structures of non-diastrophic origin - are described from the Lower Siwalik (Nahan) strata of the Haldwani-Tanakpur area. Some are epigenetic and the others are syngenetic or penecontemporaneous. The epigenetic structures simulate structures formed due to the penecontemporaneous slumping of sediments; but the presence of cross-bedding passing undisturbed through them negates this mode of origin. They are considered to be due to 'Liesegang banding'.

Among the syngenetic or penecontemporaneous structures are groove casts which are uncommon in Siwaliks. It is suggested that though there might have been occasionally grooving, the grooves were rarely preserved because of the turbulence of the environment. The other structures described comprise those due to slump deformation and intrusion of soft sediments, and those due to organic activities.