discuss evidences about neo-tectonic
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This study examines channel-scale morphodynamics of ephemeral streams in the onshore Carnarvon basin in arid west-central Western Australia. The rivers in this region have low gradients, the landscape has low relief, and the rates of climatically and tectonically driven geomorphic processes also are low. As a result, the rivers in the Carnarvon alluvial plain are highly sensitive to minor perturbations in base level, channel slope, and fluvial energy. We use channel planform adjustments, stream gradient changes, and floodplain profiles across multiple ephemeral streams within a variety of catchments and flow regimes to determine if tectonically driven land level changes are affecting channel form and fluvial processes. Growth of individual fold segments is shown to have altered stream and floodplain gradients and triggered repeated avulsions at structurally controlled nodes. Aligned perturbations in channel form across multiple channel-fold intersections provide systematic geomorphic evidence for the location and orientation of neotectonic structures in the region. These features occur as a belt of low relief anticlines in the Carnarvon alluvial plain.
The drainage pattern in the Bengal Basin as a whole has been greatly controlled by the tectonic features of the basin. Considerable evidence of significant tectonic movements has been recorded within and along the boundary of the basin in Late Tertiary and the Quaternary times. This paper tried to unveiling the signatures of neotectonic activities in the Mahananda River floodplain and its surrounding areas with the help of drainage characteristics. To carry out this interpretation historical maps, satellite imagery and earthquake records were used. The interpretation implies that the area is being structurally controlled. Changing of river courses, shifting of rivers, restriction of the Punarbhaba, Tangon and Kulic River valleys against the comparatively narrow Mahananda River, abrupt change in the sinuosity of the Mahananda River at a particular area and presence of large number of depressions/sag ponds are clear indication of the structural control of the area. In the recent past few earthquakes occurred in this region which also supports the same view about neotectonics. All these features and evidences strongly support the structural control of the area.