Wednesday, December 30, 2015

Native Americans domesticated a plant in central Mexico, teosinte, and eventually this became maize (corn). People carried seeds of maize north into the Tucson Basin about 4100 years ago. The Santa Cruz River flowed year-round and the floodplain was a lush, marshy area. By 3500 years ago, they were digging small irrigation ditches to bring water to their fields, and were probably also utilizing flood waters.

Since 1994, archaeological excavations along the Santa Cruz River, many projects associated with improvements of Interstate 10, have uncovered the settlements and fields of these farmers. Back in 2009, my company uncovered massive field systems at the sewage plant. Each small plot was surrounded by raised berms. Small irrigation ditches diverted water to plots. Nearby were a few houses and many storage pits. Nothing like it had been found before.

Another company is doing a project along I-10. Even better preserved fields have been uncovered. The farmers had prepared the area by raising berms around the perimeter of each field and digging small planting pits. The area was muddy, and adults, children, and dogs walked across the fields, the berms, and the small ditches between the berms. The mud dried, and then a sudden flash flood apparently dumped fine sand onto the area. The fields ended up being buried deeply enough that everything was preserved, almost a miniature Pompeii.

Jump ahead a couple thousand years. Dan was scraping the area and started finding berms.From there the field surface was uncovered and they started finding footprints.

Square field area, with raised berms bordering it.

I've been on two other digs where footprints were found, one along the border (horse hoof prints) and one at Fort Union Trading Post in North Dakota (oxen foot prints). 

Raised berms, which would have had water running in the area between them.

I've never seen prehistoric foot prints. On one of my digs a few years back we did find fingerprints in the mud used to coat a prehistoric house.

\Some of the foot prints were small, child-sized.

 Child foot print.

Another child's print.

Most were adult-sized. You could occasionally see the heel or the toes.

Adult foot print. The trowel is probably 8 or 9 inches long.

The footprints provide information that we have never had before. The people appear to have been mostly barefoot. Kids and dogs were in the fields with adults. You can measure individual prints and get a rough estimate of height. And so on.

I have to say, I've been an archaeologist for 29.5 years and it is still exciting to see new things and learn new things about our human past.

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