Geomorphic response to uplift along the Dragon's Back pressure ridge, Carrizo Plain, California

We used high-resolution topography, geomorphic mapping of active surface processes, and geologic mapping to study the topographic and erosional response of small drainage basins to rock uplift along the Dragon's Back pressure ridge along the San Andreas fault in the Carrizo Plain, California. We infer the history of deformation experienced by ~40 small drainage basins formed in poorly consolidated sedimentary rocks. A space-for-time substitution directly images the erosional and topographic responses to deformation. Progressive deformation and rock uplift are accompanied by increases in channel steepness and basin relief. As uplift ceases, channel concavity rapidly increases, causing channels to undercut hillslopes—this undercutting promotes the consumption of hillslopes by landsliding. This undercutting also causes basin relief to be greatest after uplift has stopped. This analysis indicates that channels of the Dragon's Back pressure ridge respond to changes in rock uplift rates over thousands of years, whereas hillslope processes may take more than an order of magnitude longer to adjust to changes in rock uplift rates. Our study directly measures changes in erosional processes due to the initiation and cessation of rock uplift, which can typically only be inferred using numerical models, by direct field observations.

[1]  Jean Braun,et al.  Numerical modelling of landscape evolution on geological time‐scales: a parameter analysis and comparison with the south‐eastern highlands of Australia , 1998 .

[2]  M. Kirkby,et al.  Hillslope Form and Process , 1972 .

[3]  Gregory E. Tucker,et al.  Hillslope processes, drainage density, and landscape morphology , 1998 .

[4]  Richard H. Jahns,et al.  Holocene activity of the San Andreas fault at Wallace Creek , 1984 .

[5]  A. Howard.  A detachment-limited model of drainage basin evolution , 1994 .

[6]  D. Montgomery,et al.  Erosion thresholds and land surface morphology , 1992 .

[7]  G. Tucker,et al.  Landscape response to tectonic forcing: Digital elevation model analysis of stream profiles in the Mendocino triple junction region, northern California , 2000 .

[8]  W. Dietrich,et al.  The soil production function and landscape equilibrium , 1997, Nature.

[9]  D. Lague,et al.  Laboratory experiments simulating the geomorphic response to tectonic uplift , 2003 .

[10]  Gary D. Egbert,et al.  High‐resolution electromagnetic imaging of the San Andreas Fault in central California , 1999 .

[11]  T. A. Black,et al.  Sediment transport by burrowing mammals, Marin County, California , 1991 .

[12]  William E. Dietrich,et al.  Hillslope evolution by diffusive processes: The timescale for equilibrium adjustments , 1997 .

[13]  Peter Molnar,et al.  Surface uplift, uplift of rocks, and exhumation of rocks , 1990 .

[14]  B. Meade,et al.  Controls on the strength of coupling among climate, erosion, and deformation in two-sided, frictional orogenic wedges at steady state , 2004 .

[15]  G. Tucker,et al.  Drainage basin responses to climate change , 1997 .

[16]  N. Snyder,et al.  Tectonics from topography: Procedures, promise, and pitfalls , 2006 .

[17]  Fritz Schlunegger,et al.  Drainage basin response to climate change in the Pisco valley, Peru , 2009 .

[18]  G. Tucker,et al.  Dynamics of the stream‐power river incision model: Implications for height limits of mountain ranges, landscape response timescales, and research needs , 1999 .

[19]  J. H. Wright,et al.  Late-Quaternary Environments of the United States , 1983 .

[20]  W. Dietrich,et al.  Hillslope evolution by nonlinear, slope‐dependent transport: Steady state morphology and equilibrium adjustment timescales , 2001 .

[21]  I. Rodríguez‐Iturbe,et al.  A coupled channel network growth and hillslope evolution model: 1. Theory , 1991 .

[22]  W. Lettis,et al.  Quaternary fold deformation associated with blind thrust faulting, Los Angeles Basin, California , 1993 .

[23]  William E. Dietrich,et al.  Valley incision by debris flows: Evidence of a topographic signature , 2003 .

[24]  E. Foufoula‐Georgiou,et al.  Channel network source representation using digital elevation models , 1993 .