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Packrat Midden Analysis, since late Pleist. Sonoran Desert History (veg & climate)

Paleo –Vegetation and –Climate of SW. Packrat Midden Analysis, since late Pleist. Sonoran Desert History (veg & climate) Alluvial Stratigraphy, since early Holocene Dry-wet and/or warm-cool periods Dendrochronology, since 300- 400 ybp Precipitation Temperature.

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Packrat Midden Analysis, since late Pleist. Sonoran Desert History (veg & climate)

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  1. Paleo –Vegetation and –Climate of SW • Packrat Midden Analysis, since late Pleist. • Sonoran Desert History (veg & climate) • Alluvial Stratigraphy, since early Holocene • Dry-wet and/or warm-cool periods • Dendrochronology, since 300- 400 ybp • Precipitation • Temperature

  2. At our starting point, 20,000 years ago…

  3. 1. Packrat middens- past 20,000 years (40,000 years of vegetation data from… packrat middens)

  4. 22,000 11,000 8,000 4,000 “Sonoran Desert” 22000-11000 ybp, Late Pleistocene • Vegetation

  5. 22,000 11,000 8,000 4,000 “Sonoran Desert” 22000-11000 ybp, Late Pleistocene • Climate relative to today:

  6. 22,000 11,000 8,000 4,000 “Sonoran Desert” 11000-8000 ybp, Early Holocene Vegetation

  7. 22,000 11,000 8,000 4,000 “Sonoran Desert” 11000-8000 ybp, Early Holocene • Climate

  8. 22,000 11,000 8,000 4,000 Sonoran Desert 8000-4000 ybp, Mid Holocene • Vegetation

  9. 22,000 11,000 8,000 4,000 Sonoran Desert 8000-4000 ybp, Mid Holocene • Climate

  10. 22,000 11,000 8,000 4,000 0 Sonoran Desert 4000 ybp - present, Late Holocene • Vegetation

  11. 22,000 11,000 8,000 4,000 0 Sonoran Desert 4000 ybp - present, Late Holocene • Climate

  12. Packrat Midden Summary for Sonoran Desert: Packrat Midden Summary for Sonoran Desert:

  13. Graphically it looks like this…

  14. And this… SW Vegetation

  15. 2. Alluvial Stratigraphy of the SW: Definitions… • Alluvium: (n) • Alluvial: (adj) • Stratigraphy: (n) • Alluvial stratigraphy: • Recent geology (Pleistocene-Holocene).

  16. 2. Alluvial Stratigraphy of the SW (Holocene)

  17. Alluvial Stratigraphy sites… “Filling in” DEPOSITION “carving out” EROSION

  18. Replication Why are sediment sites so common in SW?

  19. In The Field • It’s like a jig-saw puzzle • Distinct layers • Color • Texture • Fossils • Separated by time • Erosion • Soil Layers C-14 dated

  20. Alluvial History: Climatic Interpretation Summary

  21. 3. Dendrochronology (past 300 – 400 years) • Dendroclimatology • Subdiscipline of dendrochronology • Reconstruct past climate • Heavily replicated • Within sites • Within regions

  22. Dendrochronology recap…

  23. We’ve Seen This Before

  24. Summary Paleoenvironments of SW

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