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The mysterious rock-cut cart ruts of Malta are here examined by geomorphologists. They find that the ruts could be caused by two-wheeled carts with a gauge of l. 40m carrying [...]

Numerous landforms along the Longitudinal Valley suture of eastern Taiwan indicate that two opposing reverse faults currently dominate the suturing process between the Luzon volcanic arc and the Central Range of Taiwan. The east-dipping Longitudinal Valley fault, on the eastern flank of the valley, is well known. The west-dipping Central Range reverse fault, on the western flank of the valley, is more obscure. Nonetheless, it has produced many uplifted lateritic fluvial terraces along the eastern flank of the Central Range in the central reach of the valley, from just north of the Wuhe Tableland to near Chihshang. The fault appears to be active but blind south of Chihshang and inactive along the northern part of the Longitudinal Valley. The late Quaternary slip rate of the fault is less than 12.8 mm/yr. This constraint means that the fault is absorbing far less than half of the horizontal shortening across the Longitudinal Valley suture. However, the late Quaternary slip rate along the fault may be comparable to the uplift and exhumation rate of the Central Range. This suggests that localized brittle slip along the Central Range fault is an important component of crustal thickening and uplift of the range, even though additional shortening and crustal thickening may be occurring because of pervasive deformation beneath the range. Keywords: Taiwan, tectonic geomorphology, Central Range fault, Longitudinal Valley, sutures, exhumation.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2008.07.028 Byline: Denine Schmitz (a), Matt Blank (b), Selita Ammondt (c), Duncan T. Patten (a) Abstract: The restorative potential of dam removal on ecosystem function depends on the reversibility of dam effects and its operations. While dam removal is an established engineering practice, the need for an understanding of the ecological response remains. We used paleoflood hydrology, hydrologic modeling, and aerial photo interpretation to investigate the long-term ecologic responses to dam failure and breach. We investigated downstream geomorphic and vegetation responses to a dam failure (Pattengail Dam in 1927) and a controlled dam breach, which used natural sediment removal (Mystic Lake Dam in 1985). Our data showed vegetation responses indicative of channel and floodplain evolution at Pattengail. The size of the flood following the Pattengail dam failure initiated a series of channel adjustments and reworked over 19ha of floodplain downstream of the dam. In Mystic, we observed few flood stage indicators and a slight response in floodplain vegetation. We made several findings. (1) Dam removal effects on channel evolution and floodplain development depend on reach types and their responsiveness to flow regime change. (2) Ecologic response to dam removal depends on the sizes and timing of high flow events during and following removal. (3) Paleohydrology can be used to assess historic floods (>20 years). We see the utility of assessing the ecological responsiveness of a system to previous fluvial events or changes in flow regime. Informed about the character of a system based on its history, dam removal scientists can use these tools to set realistic restoration goals for removing a dam. Author Affiliation: (a) Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA (b) Western Transportation Institute, Montana State University, Bozeman, MT 59717, USA (c) Earth Sciences, Montana State University, Bozeman, MT 59717, USA Article History: Received 29 February 2008; Revised 29 June 2008; Accepted 30 July 2008

An exciting result of the first spaceborne radar scans of the eastern Sahara has been the recognition of drainage channels buried at depths of several metres below the dry desert sand. We relate these observations to the megageomorphological evolution of Africa and conclude that the 'radar river' valleys may have been parts of an old Nile River system rather than courses cut by a postulated westward-flowing trans-African drainage system (TADS) extending from the Red Sea Hills to the Niger Delta.