A signature of transience in bedrock river incision rates over timescales of 104–107 years

Measured rates of river incision into bedrock are commonly interpreted as proxies for rates of rock uplift (see refs 1 and 2, for example) and indices of the strength of climatic forcing of erosion over time (see refs 3 and 4, for example). This approach implicitly assumes that river incision rates are in equilibrium with external forcings over a wide range of timescales. Here we directly test this assumption by examining the temporal scaling of bedrock river incision from 155 independent measurements of river incision compiled from 14 sites. Of these sites, 11 exhibit a negative power-law dependence of bedrock river incision rate on measurement interval, a relationship that is apparent over timescales of 104–107 years and is independent of tectonic and geomorphic setting. Thus, like rates of sediment accumulation, rates of river incision into bedrock exhibit non-steady-state behaviour even over very long measurement intervals. Non-steady-state behaviour can be explained by episodic hiatuses in river incision triggered by alluvial deposition, if such hiatuses have a heavy-tailed length distribution. Regardless of its cause, the dependence of incision rate on measurement interval complicates efforts to infer tectonic or climatic forcing from changes in rates of river incision over time or from comparison of rates computed over different timescales.

[1]  L. Benda.  The influence of debris flows on channels and valley floors in the Oregon Coast Range, U.S.A. , 1990 .

[2]  M. Fonstad,et al.  Rapid Formation of a Modern Bedrock Canyon by a Single Flood Event (Invited) , 2010 .

[3]  Q. Deng,et al.  Strath terraces of Jinshaan Canyon, Yellow River, and Quaternary tectonic movements of the Ordos Plateau, North China , 2002 .

[4]  J. Roering,et al.  Fire and the evolution of steep, soil-mantled landscapes , 2005 .

[5]  H. H. Mills.  Apparent increasing rates of stream incision in the eastern United States during the late Cenozoic , 2000 .

[6]  X. Fang,et al.  Magnetostratigraphic dating of river terraces: Rapid and intermittent incision by the Yellow River of the northeastern margin of the Tibetan Plateau during the Quaternary , 1997 .

[7]  J. G. King,et al.  Mountain erosion over 10 yr, 10 k.y., and 10 m.y. time scales , 2001 .

[8]  N. Dunbar,et al.  40Ar/39Ar and field studies of Quaternary basalts in Grand Canyon and model for carving Grand Canyon: Quantifying the interaction of river incision and normal faulting across the western edge of the Colorado Plateau , 2007 .

[9]  Kelin X. Whipple,et al.  The influence of large landslides on river incision in a transient landscape: Eastern margin of the Tibetan Plateau (Sichuan, China) , 2007 .

[10]  R. Anderson,et al.  Numerical modeling of fluvial strath-terrace formation in response to oscillating climate , 2002 .

[11]  Ding,et al.  Distribution of the first return time in fractional Brownian motion and its application to the study of on-off intermittency. , 1995, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[12]  B. Burchfiel,et al.  Quaternary Climate Change and the Formation of River Terraces across Growing Anticlines on the North Flank of the Tien Shan, China , 1994, The Journal of Geology.

[13]  K. Whipple,et al.  Rapid incision of the Colorado River in Glen Canyon – insights from channel profiles, local incision rates, and modeling of lithologic controls , 2009 .

[14]  K. Wegmann,et al.  Late Quaternary fluvial terraces of the Romagna and Marche Apennines, Italy: Climatic, lithologic, and tectonic controls on terrace genesis in an active orogen , 2009 .

[15]  G. Tucker,et al.  How rivers react to large earthquakes: Evidence from central Taiwan , 2010 .

[16]  D. Lague.  Reduction of long‐term bedrock incision efficiency by short‐term alluvial cover intermittency , 2010 .

[17]  K. Whipple.  BEDROCK RIVERS AND THE GEOMORPHOLOGY OF ACTIVE OROGENS , 2004 .

[18]  William E. Dietrich,et al.  Modeling fluvial erosion on regional to continental scales , 1994 .

[19]  Gregory E. Tucker,et al.  Bedrock channel adjustment to tectonic forcing: Implications for predicting river incision rates , 2007 .

[20]  Chris Paola,et al.  Shredding of environmental signals by sediment transport , 2010 .

[21]  Anthony,et al.  A LATE TERTIARY ORIGIN FOR MULTILEVEL CAVES ALONG THE WESTERN ESCARPMENT OF THE CUMBERLAND PLATEAU , TENNESSEE AND KENTUCKY , ESTABLISHED BY COSMOGENIC 26 AL AND 10 BE , 2004 .

[22]  D. Fabel,et al.  Pliocene−Pleistocene incision of the Green River, Kentucky, determined from radioactive decay of cosmogenic 26Al and 10Be in Mammoth Cave sediments , 2001 .

[23]  Marc W. Caffee,et al.  Incision and differential bedrock uplift along the Indus River near Nanga Parbat, Pakistan Himalaya, from 10Be and 26Al exposure age dating of bedrock straths , 1998 .

[24]  P. Sadler.  Sediment Accumulation Rates and the Completeness of Stratigraphic Sections , 1981, The Journal of Geology.

[25]  K. Wegmann,et al.  Holocene strath terraces, climate change, and active tectonics: The Clearwater River basin, Olympic Peninsula, Washington State , 2002 .

[26]  Sean D. Willett,et al.  Fluvial bedrock incision in the active mountain belt of Taiwan from in situ‐produced cosmogenic nuclides , 2005 .

[27]  Douglas J. Jerolmack,et al.  Scaling laws for aggradation, denudation and progradation rates: the case for time-scale invariance at sediment sources and sinks , 2014 .

[28]  Douglas J. Jerolmack,et al.  Transience and persistence in the depositional record of continental margins , 2007 .

[29]  A. Wilson,et al.  Hydraulic geometry, river sediment and the definition of bedrock channels , 2008 .

[30]  Nicholas Brozovic,et al.  Bedrock incision, rock uplift and threshold hillslopes in the northwestern Himalayas , 1996, Nature.

[31]  P. Knuepfer,et al.  Adjustments by the Charwell River, New Zealand, to uplift and climatic changes , 1987 .

[32]  Rina Schumer,et al.  Real and apparent changes in sediment deposition rates through time , 2009 .

[33]  G. Stock,et al.  Rates of erosion and topographic evolution of the Sierra Nevada, California, inferred from cosmogenic 26Al and 10Be concentrations , 2005 .

[34]  O. Korup,et al.  Millennial lag times in the Himalayan sediment routing system , 2013 .

[35]  C. Shuman,et al.  Geomorphic and tectonic process rates: Effects of measured time interval , 1987 .

[36]  S. F. Personius,et al.  Late Quaternary stream incision and uplift in the forearc of the Cascadia subduction zone , 1995 .

[37]  M. Brandon,et al.  A Fluvial Record of Long-term Steady-state Uplift and Erosion Across the Cascadia Forearc High, Western Washington State , 2001 .

[38]  M. Abdelsalam,et al.  Blue Nile incision on the Ethiopian Plateau: Pulsed plateau growth, Pliocene uplift, and hominin evolution , 2007 .

[39]  S. Redner.  A guide to first-passage processes , 2001 .