Figure 3. Width changes in formerly antecedent channels crossing small growing folds in the Mackenzie Basin, New Zealand. A. Surveys of abandoned channels just upstream of a fold and in its core reveal 3- to 5-fold decreases in width as channels traverse a fold. Note that because loess and soils have partially filled the abandoned channels, their former geometry was reconstructed using closely spaced soil probes. B. Channel incision is measured by surveying the height difference between the channel bottom and the uplifted former terrace surface across the asymmetric fold. C. Compilation of data from five channels shows that 1 to 2 meters of uplift causes a 5- to 10-fold channel narrowing. For these small channels, incision of more than 3 m causes little further narrowing, probably due to wall effects on channels only a few meters wide. Modified after Amos and Burbank (2007).
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Oct9 09
