The Magnetometer Does Not Lie

In my conversations with Dr. Chet Walker over the last couple of years, he’s said this on several occasions: “The magnetometer does not lie.” The magnetometer accurately reflects what is buried in the ground. However, this does not mean that every magnetic anomaly viewable in the Moundville survey map represents a prehistoric feature. To the contrary, many represent modern metal trash: nails, tent pegs, rusty pin flags, old bullets, bits of wire. We certainly have hit a bit of that during past seasons of the MPP. But after the first full week of this summer field season, we’ve yet to hit anything of the sort. All but one of our excavation units have already uncovered ancient architectural remains.

The indigenous peoples of the eastern United States rarely built in stone. Their construction materials came from the hard- and softwood forests, cane-choked riverbanks, and red and yellow clay seams that could have been found within an arrow shot of most settlements. Nowadays, little more than stains in the soil are all that can be found of most prehistoric houses, temples, and civic buildings, but stains in the soil are enough for the purposes of Southeastern archaeologists. And we get excited about such things!

Artist’s rendition of a Mississippian house. The remains of several types of houses have been found at Moundville. This is the wattle-and-daub type that was often raised in wall trenches.

Team 1’s quick but careful excavation in the northwestern plaza has revealed a series of wall trenches which we believe are sections of the north wall of a large, square building that postdates plaza construction. Wall trenches are the hand-dug slots into which the Moundville people lowered pre-fabricated sections of wooden wall. This construction technique was once quite widespread in the southeastern United States, practiced by populations from as far north as Illinois, south as Florida, and west as Oklahoma. It was dominant at Moundville throughout the 14th, 15th, and 16th centuries. One of the Team 1 wall trenches has already been excavated. Judging by its depth – approximately 80 centimeters (almost 3 feet) – the associated building must have been quite substantial. The locations of old posts removals can still be seen at the base and sides of this excavated wall trench.

Team 1’s first unit. Note the two yellowish brown strips cross-cutting the unit. These are the wall trenches that the magnetometer picked up on.

An excavated wall trench. The trench probably originally began at the plaza surface, but its shallowest portions were destroyed by plows during the 19th and 20th centuries. We noticed the stain as soon as the “plowzone” had been removed.

Erik Porth and Daniel Cardwell are mapping the contours of the excavated wall trench. We have forms for just about any situation and are careful to document everything we encounter.
Erik and Daniel are already such good friends that they have decided to coordinate their clothing for the remainder of the summer. They bring an unprecedented level of panache to the MPP.

On Thursday, we doubled the size of Team 2’s 1-x-2 meter unit in order to get a better idea of what exactly they’d encountered. Before expanding, we noticed a yellowish sandy area taking up the southwest quadrant of their unit. It stood out because the rest of the unit consisted of the reddish-brown clay-rich soil that is typical of plaza area. We now know that this sandy zone extends straight to the south, still with the reddish-brown clay surrounding it. We are beginning to think that Team 2 has uncovered the top of a square-sided pit, probably the semi-subterranean floor of a square pit house. The magnetometer map shows what appear to be clusters of small houses in this area (see Team 2 mag image in “The First Two Days” post, below). I’ll post photos of Team 2’s excavation unit after we get a good shot on Monday.

Aaron Posey is measuring the depth of the unit to make sure we keep things uniform and accurate.

Team 3 has already completed its first unit. That’s because we hit sterile subsoil right under the plowzone! Most people probably think that you can put a shovel in anywhere at Moundville and turn up interesting things, but that’s simply not the case. Team 3’s first unit was a bust – no artifacts, no archaeological features. We had expected to find a large post (see Team 3 mag image in “The First Two Days”), so this left me a bit baffled as to what could have caused the magnetic anomaly. But don’t lose heart! Soon thereafter, we began our second unit less than 6 meters from the first and, lo and behold, revealed what looks like a good-sized post stain right where one should be. Team 3’s top priority on Monday is to figure out if this stain is, in fact, what we think it is. I’ll keep you “posted,” as usual!

Traci Roller and Kimberly Peace had a good time mapping profiles on Friday.

See the dark circular post stain in the lower right quadrant? This post was probably erected after the plaza was constructed.

A dragonfly dropped by to impress us with his size, but we didn’t think he measured up.


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