Micro sample 571

Wahl et al. (2006:384) state that "A single Zea grain (61 Am long axis; axis/ pore ratio, 5.5) was encountered at the 3.15-m level, indicating that there may have been agricultural activity in the Mirador Basin as early as 4600 cal yr B.P." This Zea pollen grain is most likely maize and is most closely associated with an AMS radiocarbon date on assorted organic material, including charcoal, macroscopic plant fragments, wood, and macroscopic insect fragments, recovered from slightly deeper in the core, at 3.42 m. Though the pollen grain comes from near the base of Zone 3, the AMS sample dates the uppermost levels of the earlier Zone 4 and so very likely pre-dates the earliest maize pollen by several centuries.