1. 1.Packrat Midden Analysis, since late Pleist. –Sonoran Desert History (veg & climate) 2.Alluvial Stratigraphy, since early Holocene –Dry-wet and/or warm-cool periods 3.Dendrochronology, since 300- 400 ybp –Precipitation –Temperature Paleo –Vegetation and –Climate of SW

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

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

4. “Sonoran Desert” 22000-11000 ybp, Late Pleistocene Vegetation 22,00011,0008,0004,000

5. “Sonoran Desert” 22000-11000 ybp, Late Pleistocene Climate relative to today: 22,00011,0008,0004,000

6. “Sonoran Desert” 11000-8000 ybp, Early Holocene Vegetation 22,00011,0008,0004,000

7. “Sonoran Desert” 11000-8000 ybp, Early Holocene Climate 22,00011,0008,0004,000

8. Sonoran Desert 8000-4000 ybp, Mid Holocene Vegetation 22,00011,0008,0004,000

9. Sonoran Desert 8000-4000 ybp, Mid Holocene Climate 22,00011,0008,0004,000

10. Sonoran Desert 4000 ybp - present, Late Holocene Vegetation 22,00011,0008,0004,000 0

11. Sonoran Desert 4000 ybp - present, Late Holocene Climate 22,00011,0008,0004,000 0

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

13. Graphically it looks like this…

14. SW Vegetation And this…

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

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. It’s like a jig- saw puzzle Distinct layers –Color –Texture –Fossils Separated by time –Erosion –Soil In The Field 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

25. Summary Paleoenvironments of SW