|
INTRODUCTION The USGS in conjunction with NMBMM, BLM, UNM, etc. is conducting a survey of the Rio Puerco Basin to: - compare present and past erosion rates - determine controls on present sediment yields - map erosion potential - determine perods and rates of past arroyo filling - model arroyo processes This multi-discipline project has produced a GIS, available at: climchange.cr.usgs.gov, and publications listed in the bibliography. The FOP trip will focus on the areas around San Luis (fig. 1) and La Ventana in the northern end of the basin.
ROAD LOG Depart from Socorro, drive north on I-25. Figure 1 shows a Landsat image of the entire Rio Puerco basin. I-25 follows the Rio Grande and the narrow divide between the Rio Grande and the Rio Puerco can been seen from Bernardo north. Pass through Albuquerque, proceed about 20 miles to exit # at Rt. 44 just north of Bernallilo. Proceed west on Rt. 44 (check the Cuba HS roadguide). Stop just east of Santa Ana Pueblo? Note - the dunes on the divide - the Rio Grande rift and Sandia Mtns to the east. - Jemez River draining the Jemez Mtns to the north. Proceed to San Ysidro, continue west on Rt. 44. Note - Sierra Nacimiento to the northeast. - tilted blocks of plateau rocks (Jim: can you i.d. the units) - color changes in alluvium of the Rio Puerco with changes in bedrock Turn west at mile xxx on Rt. 179 toward San Luis.
SAN LUIS AREA Descriptions of: - terraces and channel geometry - alluvial stratigraphy of the pipeline crossing - gravel pits and soils - arroyo Chavez erosion data: Gellis, Clapp
ROAD LOG Return to Rt. 44 via Rt. 179. Turn north on Rt. 44 to La Ventana
LA VENTANA AREA Overview of headcut caused by diversion of Rt. 44 (Love and Gellis) Pediments east of Rt. 44 (map from Kirk Bryan), soils on pediments. --------------------------------------------------------------------------------------------------- In addition, we may generate some verbage on the following topics for the 98FOP: Rio Puerco: climate, processes and timescales (or climate, cows and chaos) 1. Long-term erosion rates: >100m/Ma - downcutting rates relative to dated surfaces - geomorphic paleosurfaces? - cosmogenic rates in Chavez and basin scale
2. Dynamic Equilibrium of long-term downcutting: grading of uplands to channels via shale slopes: - hillslope erosion: arroyo chavez - channel erosion - lags in channel response to hillslope erosion (pleist/holocene; 6ka) - tracing a quartz grain through the system: storage history 3. Small basin processes: - piping: relation to summer storms - bank collapse: related to high flows? - overland flow on shale slopes, particle detachment and movement - hyperconcentrated flows 4. Post-incison recovery: processes over the last 50 years: rate of arroyo filling disequilibrium channel processes (cutoffs,knickpoints, aggradation, incision) 5. The arroyo cycle revisited: revision of Elliott’s model: the arroyo channel is a dynamic place. In flood, tremendous volumes of sediment are eroded and redeposited. The net result is a transit time of.......x cycles.
|