Geomorphic observations of rivers in the Oregon Coast Range from a regional reconnaissance perspective

Active tectonic influence on the evolution of drainage and landscape: Geomorphic signatures from frontal and hinterland areas along the Northwestern Himalaya, India

“…Prominent indicators are the development of a sharp morphology along active fronts, mountain front sinuosity, entrenched channels, or a high degree of incision along the channels flowing across active faults, the formation of linear valleys along fault traces, a sudden change in channel morphology, a sudden change in the base level of the channel floor -marked by pronounced knick-points in the river profiles etc (e.g. Bull and McFadden, 1977;Bull, 1984;Seeber and Gornitz, 1983;Ouchi, 1985;Wells et al, 1988;Rhea, 1993;Schumm et al, 2002;Silva et al, 2003;Riquelmea et al, 2003;Bishop et al, 2003). For the identification of tectonically controlled geomorphological features, along with the Survey of India Toposheets (1:50,000 scale), high resolution CORONA declassified satellite photos with stereo-pair to view the terrain in 3-D were used.…”

“…As mentioned earlier geomorphological indexes developed by Bull and McFadden (1977) have been used extensively and tested as a valuable tools in tectonically active areas, such as the SW USA (Bull and McFadden, 1977;Rockwell et al, 1984), Costa Rica (Wells et al, 1988), Oregon Coast Range, USA (Rhea, 1993), the Kachchh region, India (Sohoni et al, 1999), southeast Spain (Silva et al, 2003) and western Taiwan (Chen et al, 2003). For this study two indexes: Valley width/height ratio (Vf) and Mountain front sinuosity (Smf) studied by Mohanty (2004) were taken into consideration, since the combination of these two indexes allows the inference of tectonic activity along the faulted fronts (Silva et al, 2003).…”

“…provide a wealth of information which assists our understanding of the influence of tectonics on landscape change and drainage evolution (e.g. Bull and McFadden, 1977;Seeber and Gornitz, 1983;Gregory and Schumm, 1987;Wells et al, 1988;Rhea, 1993;Demoulin, 1998;McCalpin, 1996;Malik et al, 2001;Burbank and Anderson, 2001;Champel et al, 2002;Schumm et al, 2002;Silva et al, 2003;Riquelmea et al, 2003). It has also been suggested that an understanding of past drainage evolution may be derived from present-day river patterns, which provide an insight into past deformational events within active mountain belts (Friend et al, 1999).…”

Systematic variation of bedrock channel gradients in the central Oregon Coast Range: implications for rock uplift and shallow landsliding

“…Over 100 years of riparian wood removal and accelerated shallow landsliding may have also contributed to the dominance of bedrock (Montgomery et al, 2000). Persistent strath terraces along most OCR channels attest to the long-term requirement of OCR streams to incise bedrock, and evidence of stream capture (Neim, 1976;Baldwin, 1986;Chylek, 2002) and variations in stream profile form (Rhea, 1993) are likely indicative of long-term Quaternary rock uplift. Debris flows generated from unchanneled valleys are often triggered by storm events and periodically scour steep, low-order channels.…”

Application of DEM, Remote Sensing and Geomorphic Studies in Identifying a Recent [or perhaps Neogene?] Upwarp in the Dibru River Basin, Assam, India

“…The index (Vf) was proposed to identify the areas of tectonic quiescence and areas that have been recently uplifted (Rhea, 1993). In the present study the values of Vf were ascertained at five segments of the Dibru basin, viz.…”