1. Michelle Trogdon GEOG 5401 Soils Geography Fall 2007 – Univ of Colorado, Boulder

2. analyze 1 soil profile associated with features to distinguish features in eroding contexts soil chemistry sifting through bad photos without scales aid future Master’s project

3. Oaxaca Mixteca Alta Nochixtlan Valley

4. refers to leveled land on otherwise hillslope method of soil conservation mitigate erosion water and nutrients residential, agricultural terraces, both?

5. Formative (900BC-AD200) agricultural production begins in Mixteca population dispersed on low piedmont Classic (AD200-800) hilltop towns are established population expands Postclassic (AD 800-1450) caciques (codices) commoner farmers increased terraced landscape around cacicazgos

6. No significant type change through Classic- Postclassic When did retention terraces begin in Formative? previously buried now eroding may provide insight into agricultural adaptation clearing land creates erosion El Palmillo (V. of Oaxaca) “paved” terraces increases runoff semi-arid environment and high clay content odds for shrink-swell, need to control soil moisture

7. informal “rock-piling” of river rocks 5-30 cm upslope wider base, ~1m above soil surface boulders 40-50cm downslope (drystone) 1-3m below soil surface chronological congruency Ethno evidence- still in use today Labor community-level or few households

8. natural fill, multiple events backfill Stratigraphy indicators Soil dating balance of moisture, nutrients Nitrogen, phosphorous Semi-arid more CaCO3, fixes PO4 adding N makes plants (grasses) more efficient with less water N fixers require more P

9. Table 1. The features measured in this study. SiteFeatureLengthMaxiumMinimumArtifactsStyle (cm)Height (cm) EtlatongoF18020 nonesmall pebbles diagonal YanhuitlanF1100157potteryloose angular cobbles 3-10 cm YanhuitlanF111254015nonelarge rounded cobbles 5-15 cm YucuitaF77504020nonerow of large boulders YucuitaF11309070none large range of size cobbles to boulders, ontop of gravel

10. On top of Paleosol 4 Radiocarbon dates from soils 600-8520BC blocky structure = more clay, drier climate more CaCO3= more PO4

11. P3 P4 1. Reduce runoff erosion and retain some water and nutrients 2. Reduce collecting water saturating clay-rich soil and damaging soil quality

12. soil info date PO4 and pH soil indicators upslope and downslope

13. More details regarding relationship to soils orientation of walls = erosion patterns and stream migration associated soils throughout valley, erosion and deposition events excavation of coeval terraces on hilltops and valley floors practices vary with time or topography