Tuesday, May 13, 2008


We've just finished the current phase of fieldwork out in the Imperial Valley and I'll try to do some catch up posts to talk about some of our finds. My apologies for my long pause in posting.

We found quite a few groundstone artifacts on our survey. Above you can see a mano (hand stone) and metate (grinding slab) found on the surface next to each other. The Kamia who lived in the area in late Prehistory, were opportunistic farmers who grew maize and beans and used the manos and metates to grind corn meal.

If you look closely at this fine slab metate you can see the pecking scars that were used to shape it and to "sharpen" it after use. The glassy-smooth ground surface of the metate would have to be roughened periodically to more efficiently grind corn.

This picture shows an unusual discoidal shaped mano. In addition to maize, these implements were also used to process various wild plant seeds as well as mesquite beans.

This last find really surprised us. You see me in the picture above holding a large pestle. It's very heavy and made of granite that must come from the mountains twenty miles or more west of where we found it on the desert floor.

Stone mortars and pestles are representative of acorn processing technology that is very common in the non-desert portions of California. The Kumeyaay who lived in the mountains where this pestle came from, processed acorns from the oaks that grew there, and traded the meal for maize with the Kamia who lived down here in the desert and had no oaks of their own.

This pestle would have been pretty useless where we found it. It was found all by itself, no other artifacts or features in association. As heavy as it is and as far as it had been carried, you can just imagine someone on a hot day a few hundred years ago dropping it and saying, "I not carrying this thing another step!"


Matt Mullenix said...

Welcome back!

So, explain to me: these things are just lying around because people were walking through the bad lands, or were they camped there? Did it look prety much like it does today? Give us some context.

Peter said...

My guess would be that the mountain tribe sent whole rather than ground acorns to the desert tribe, perhaps because ground ones would go bad more quickly, and hence the desert tribe had to acquire a pestle. If they had received already ground acorns they'd have no need for a pestle. No one would carry a heavy pestle 20 miles without good reason.

Reid Farmer said...

Matt - there are large camps near by, the project area is on the shoreline of a prehistoric lake (Lake Cahuilla) now dried up with the exception of the Salton Sea that refilled after a Colorado River flood earlier in the 20th century. The climate was pretty much the same as now during late prehistory, but there was water to attract people to the area.

Peter - that is a very reasonable surmise, but we would be finding more pestles (and probably stone mortars) if that were the case. This find was highly unusual.