Fire on the Mountain: Earth Oven Features in Nevada

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Sheep Range roasting pit with banana yucca (foreground) and Joshua trees (background) growing around it.

Editor’s Note: This blog piece was written in 2016, but is only now being posted owing to …  the distractions of ASWT research.  Spencer, a stalwart member of the 2016 ENC crew, has returned to southern Nevada where he is again working on the Desert National Wildlife Refuge.

By Spencer Lodge

Hello everyone, this blog is a little different than previous posts.  Instead of focusing on work we accomplished in Eagle Nest Canyon, I will highlight what I have learned about the earth oven facilities I recorded in southern Nevada as part of my 2016 M.A. thesis at Texas State University, “Fire on the Mountain: Roasting Pits in the Sheep Range on Desert National Wildlife Refuge.” (Google the title if you would like to read my thesis.) My study area represents an interesting contrast with the Lower Pecos Canyonlands, a contrast I appreciate all the more after spending six months (Jan-June 2016) helping to excavate and document the copious evidence of earth oven cookery at Eagle Cave and Sayles Adobe.

Before moving to Texas for grad school, I worked on the Desert National Wildlife Refuge located some 20 miles north of Las Vegas. While working there I recorded nearly 200 roasting pits (i.e., ring middens) throughout the Sheep Range, the primary mountain range on the Refuge. When researching graduate programs, I was attracted to Texas State University due to the focus on earth oven technology by Dr. Black. Even though 1,000 miles separate southern Nevada and southwest Texas, I find the similarities in earth oven technology between both areas to be quite interesting.

My Study Area

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Satellite image of the Sheep Range within the Desert National Wildlife Refuge (red) where my research was conducted.

My study focused on the Sheep Range, located roughly 20 miles north of Las Vegas in southern Nevada, in the fuzzy boundary between the Great Basin to the north and Mojave Desert to the south. The Great Basin, known for its internal draining system which resulted in pluvial large lakes during the Late Pleistocene and Early Holocene, is evidenced by the Desert Dry Lake located directly northwest of the Sheep Range. Flora associated with the Mojave Desert is located at various ecoregions spread across the Sheep Range, including Utah agave, Joshua Trees, Banana Yucca, and Mojave Yucca.

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Utah agave (left) and banana yucca (right), two of the plants that were likely baked in Sheep Range roasting pits.

The extremes are very apparent in southern Nevada, from the bone dry playa beds up to pinion covered mountains. This region is dry, receiving 2-7 inches of rain per year in the lowlands, and up to 16-25 inches in in upper elevations (Mayer et al. 2012:30). Reliable water sources in the immediate area consisted of springs scattered throughout the Sheep Range. Due to the aridity and extreme nature of the landscape, prehistoric peoples in the region were highly mobile with relatively low population density. In fact, the Southern Paiute (or Nuwuvi) who inhabited southern Nevada at the time of Euroamerican contact had the lowest population density of any group in the Great Basin.

Ethnographic accounts for the use of roasting pits by Southern Paiute suggest this method of cooking was used for numerous plant foods, including agave, various species of yucca, and green pinyon pine cones.

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View of a roasting pit (foreground) surrounded by Joshua trees and black brush with the Desert Dry Lake in the background.

Recording and Studying Roasting Pits

While conducting a survey on the Desert National Wildlife Refuge where the Sheep Range is found, I documented my first roasting pit. These earth oven facilities are comprised of rock, carbon-stained sediment, and charcoal, all by-products of hot-rock cooking. A typical roasting pit has a circular shape with a sunken central depression where the oven was built. To my surprise, a significant amount of the thermally-altered rocks were white, allowing us to spot the features several hundred meters away even with a pinyon tree growing from the center.

Even more surprising, the density of white rock allowed me to find more than 250 roasting pits using aerial imagery. The process I used to find these sites was rather straight-forward. Using Google Earth, I scanned the canyons and alluvial fans extending from the Sheep Range, staying at an average eye elevation of 7,000 ft. Potential roasting pits were marked to be verified in the field.

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A volunteer writes the photo log as I (background) search for associated artifacts.

In the field, roasting pits were measured, photographed, and the surrounding landscape was surveyed for associated material culture or additional roasting pits initially unidentified. Three primary types of measurements were taken: the diameter of the midden, the diameter of the sunken depression, and the size of the cooking pit when identifiable. Height measurement were taken as well, but deemed unreliable as I was unable to know exactly where the roasting pit midden ended and the topography underneath began.

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Schematic model of roasting pit showing the terminology used by Lodge (2016).

Observations focused on the type of vegetative zone and topographical setting in which the feature was constructed, as well as how one roasting pit differed from those around it. (For example: Was it smaller? Did it appear more eroded or infilled? Was it located closer to resources?) Once a roasting pit was recorded, we either hiked or flew to the next one on my list. I was fortunate to have the aid of a helicopter to access the more isolated roasting pits, which was terrific given the rugged and generally undeveloped nature of the Sheep Range. In total, 193 roasting pits were recorded and another 30 potential cooking features were identified. After the end of this field project, I recorded an additional 10 roasting pits.

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Example of a roasting pit that is smaller, more ephemeral than most, and partially filled in with sediment. Visible in the background is the helicopter that allowed me to access remote features.

Analyzing Roasting Pits

I was unable to excavate or perform any destructive forms of analysis to the feature or cultural materials found in association. Instead I decided to analyze roasting pit distribution and size measurements throughout the Sheep Range using a combination of statistics and ArcGIS. Statistical tests were used to see if roasting pit size varied significantly according on the vegetative zone it was built in, and to test the usefulness of my identification method in areas with poor visibility (tree cover). ArcGIS was used to see if roasting pits were more often built in clusters or equally distributed, and if clustered, whether “hot spots” of use could be identified. I also conducted thermal testing on rock samples and used X-Ray Defraction (XRD) to determine the material type as well as the reason why thermally-altered rocks turn and remain white.

For both statistical and GIS analysis, I looked at midden size as an indication of use. That is to say, since each cooking event results in additional waste in the form of spent rock, charcoal, carbon stained sediment, etc., I infer that roasting pits with larger middens were used more often than those with smaller middens. I measured the length and width of each midden (Exterior), as well as the interior depressions.

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Example of a well-defined roasting pit with the central cooking depression covered in vegetation.

 

Both methods of analysis taught me several things. First, roasting pits built in lower elevation vegetative communities (such as the Creosote Brush Community) were smaller on average than those built in higher elevation communities (such as Mixed Shrub or Pinion/Juniper Communities). Since both fuel and food resources diminish along with elevation, higher elevation sites allowed people to revisit locations more frequently, increasing midden size more quickly in the process.

Second, GIS analysis indicates roasting pits were more often built in groups, as opposed to constructed evenly throughout the Sheep Range. Hot-Spot GIS analysis also highlighted certain portions of the Sheep Range where larger roasting pits were concentrated, suggesting these locations were more often frequented for baking foods.

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Scatter plot showing the relationship between roasting pit size and elevation.

Cooking Features in Nevada and Texas

Like the burned rock middens of the Lower Pecos, the roasting pits of southern Nevada are synonymous with earth oven facilities. The term earth oven facility refers both to the cooking pit where foods are baked and to the associated debris created from cooking (spent rocks, charcoal, etc.). Roasting pits are comprised of a central depression where foods were baked and a surrounding ring midden.

One critical difference between earth oven features in southern Nevada and southwest Texas is the amount of excavation they have received. Here in Nevada, roasting pit excavation has been minimal compared to the extensive work done in Texas. Recovered botanical remains from several roasting pits suggest agave, yucca, and meat were all cooked within. Just over 60 radiocarbon dates have been obtained from southern Nevada roasting pits, mostly dating to the past 2,000 years and as far back as 3,800 B.P. In comparison, there are now hundreds of radiocarbon dates from earth oven facilities in southwest and central Texas! Ring middens are also present in Texas, however they tend to have larger accumulations of fire-cracked rock and occur in both open air and rockshelter settings. While earth ovens have been found in rockshelters in Nevada, roasting pits are found only in open settings.

Color Change

Perhaps the most striking difference between the earth oven facilities of the Lower Pecos Canyonlands and those of southern Nevada is how visible they are on the landscape. Roasting pits in the Sheep Range are overall much easier to spot due in part to their color. When heated to temperatures exceeding 875° C, dolomite and limestone, the preferred material type for pit roasting in the Sheep Range, changes color from gray to white. Roasting pit middens are not entirely comprised of white rocks, but rather a mixture of bleached and natural colored rocks. However, even a relatively minimal amount of white rocks intermixed within a midden allows roasting pits to stand out against the otherwise drab landscape.

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An up close example showing the mixture of white and natural colored rock found with a roasting pit.

Limestone was also commonly used in earth ovens in southwest Texas, but in contrast to southern Nevada, burned white rocks are not commonly found. For example, while excavating in Eagle Cave in 2016 I encountered less than ten white limestone rocks among the many hundreds of fire-cracked rocks I handled. Instead, the burned limestone rocks in the Lower Pecos are typically dark gray in color after use, sometimes exhibiting a pinkish hue.

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Nevada dolomite before (left) and after (right) being heated to 900 C.

Size Variation

Another reason why the Sheep Range roasting are apparent on the landscape is due to their size. On average, roasting pits were nearly a meter in height at their peak with a maximum recorded height of over two and a half meters! When you consider that roasting pits were commonly built in areas lacking tall vegetation, they simply had nowhere to hide.

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A very impressive two and a half meter tall roasting pit in the Sheep Range.

Conclusion

Since wrapping up the 2016 field season at Eagle Nest Canyon, I have returned to southern Nevada to work once again at the Desert Refuge. Using what I’ve learned researching earth ovens in Eagle Nest Canyon, I intend to continue investigating roasting pits throughout the Range (I’ve already recorded another ten features, bringing my total to 203!).  I also hope to explore the experimental use of earth ovens and perhaps one day I’ll have the opportunity to excavate one of the roasting pits of southern Nevada.   Until then I’ll keep looking up at the Sheep Range and thinking about times not so long ago when the Chemehuevi, a Southern Paiute group, frequented the area.

“One could tell from great distances when people gathered mescal [and] see fires on all the mountains.”

 

Lodge, Spencer N.
2016    Fire on the Mountain: Roasting Pits in the Sheep Range on Desert National Wildlife Refuge. M.A. thesis, Anthropology, Texas State University.

 

 

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Eagle Cave South Trench 2015: Cleaning the Kitchen at Feature 8

By Bryan Heisinger

**The next four blog posts will each showcase a different Profile Section that was documented and sampled during the 2015 field season. Each of these Profile Sections has different sediment characteristics, artifacts, and ecofacts. The first is Profile Section 17 and Feature 8, located closest to the rear wall. For a location map see the previous post, 2015 Investigations at Eagle Cave.**

Bryan standing next to his poster at TAS.

Bryan standing next to his poster at TAS.

During the Ancient Southwest Texas Project’s 2015 Eagle Nest Canyon Expedition, the crew uncovered and sampled Feature 8—an earth oven pit and intact heating element complex near the back of Eagle Cave (see Between a Rock and a Heart Place). The dense concentration of large fire-cracked-rocks (FCR) and charcoal within the pit are classic characteristics of earth oven baking. Further, many of the limestone rocks were large (11-15 cm) in size and inclined in a basin-shaped configuration at the base of the pit. The matrix that surrounded these fire-cracked rocks (FCR) was heavily organic, ashy, rich with dime-size charcoal chunks, and almost entirely absent of artifacts.

Plan and profile views of Feature 8 as originally exposed in Unit 25. Notice the large FCR, and how they are inclined towards the right.

Plan and profile views of Feature 8 as originally exposed in Unit 25. Notice the large FCR, and how they are inclined towards the right.

Digital Elevation Models (top) and orthographic photos (bottom) of Feature 8 during excavation of Unit 25 Layer 3. Contour interval is 2 centimeters. Elevations range from 980.138 meters (brown) down to 979.445 meters (blue).

Digital Elevation Models (top) and orthographic photos (bottom) of Feature 8 during excavation of Unit 25 Layer 3. Contour interval is 2 centimeters. Elevations range from 980.138 meters (brown) down to 979.445 meters (blue).

Methodology

After initially exposing Feature 8 in Unit 25, Units 50 and 55 were opened up as sampling units. The two units were excavated following natural stratigraphic layers, and matrix samples were collected from each layer. Back in the lab, each matrix sample was sifted through a ½ inch sieve and all artifacts and were collected and bagged by type. The remaining matrix was split into 1 liter samples for curation and further analysis by our various colleagues (archaeobotany, geoarchaeology, and entomology). All rocks greater than 2.5 cm were added to the Rocksort data. Profile Section PS17 is the east/west running profile of excavation units 50 and 55. After cleaning the profile, a 3D model was created using Structure from Motion (SfM) photography  and the stratigraphic layers (strats) were annotated on an orthophoto of the profile.

PS017 Profiles

 

PS017 Debitage

PS017 Rocksort

Preliminary Interpretations and Observations

Based on the densities of large FCR  (> 11-15 cm), organic soil, and heavy concentrations of charcoal,  PS17 appears to be located in an area of Eagle Cave that has been used for repeated earth oven events over the centuries, of which the Feature 8 pit is just the most recent iteration.

Some interesting observations:

1) Besides charcoal and other carbonized plant remains, there was no uncharred organic material in the Feature 8 complex.

2) 110 + kg of burned limestone rock from Feature 8 was counted and quantified from Units 50 and 55. Many of these rocks were >15 cm, indicative of the “pristine” rocks expected in an earth oven heating element.

3) The amount of large FCR in the PS17/ F8 area relative to the units closer to the dripline, indicate that this area was favored for earth ovens pits. The tossing of discarded rocks during cleaning episodes would have sent smaller rocks and fiber toward the dripline.

4)  A hard/cemented matrix was encountered in layer 3 of Units 55 and 50. The formation process and composition of this anomaly is awaiting further analysis.

 

**A full PDF version of the poster is available here: Heisinger_TAS2015_Feature8_FINAL

Between a Rock and a Heart Place

By Bryan Heisinger

Last year during the 2014 Eagle Nest Canyon Expedition, the crew surveyed the land around the Shumla campus for a fresh spot to establish an experimental earth oven facility. As described by Jake Sullivan and Brooke Bonorden (see Searching for the Trifecta), earth ovens are a cooking technology used by the people of the Lower Pecos (and across the world) to bake plants and animals that would otherwise be inedible to humans.

The remains of earth ovens are found at thousands of archaeological sites across the Lower Pecos Canyonlands region, including Eagle Nest Canyon.  At Eagle Cave, the massive heep of earth oven cooking debris–mainly fire-cracked rock (FCR)–has accumulated from the repeated use of the site for constructing earth ovens, probably over thousands of years. Though highly recognizable and important to our understanding of the human occupation and use of Eagle Cave, the many hundreds of tons of burned rock that fill this and other rockshelters within Eagle Nest Canyon has been poorly studied and documented by archaeologists who have worked here over the past 80 years.

In reaction to this negligence towards FCR and earth oven research, the ASWT project has made it a priority to study and quantify the amount of earth oven cooking that occurred in the uplands and rockshelters in and around Eagle Nest Canyon.  As we documented in 2011-2012, similar evidence can be found along Dead Man’s Creek, a tributary of the Devils River, and across the region and beyond. When studying earth ovens, one of the best ways to become acquainted with the methods of earth oven technology  is to use experimental archaeology and actually build one!

The ASWT Experimental Earth Oven:

Back in 2014 when we were surveying the Shumla campus for a suitable spot to build earth ovens, we had three criteria to keep in mind while looking for the perfect location: 1. Soil, 2. Fuel,  and 3. Food. Not to mention, we took care to avoid establishing an oven at a known archaeological site! Soil, fuel, and food are the desirable location traits needed for a successful earth oven, because you need soil to dig an oven pit, you need wood to build a fire, and you need food (in our case sotol or lechuguilla) to cook. The crew eventually found a favorable spot near campus and cleared the surrounding brush for the ASWT Experimental Earth Oven locality.  Unfortunately, due to burn bans, lack of time, and conflicting personal schedules, the 2014 ENC expedition was never able to build an experimental earth oven

Fast forward to this year: On January 11th, three days after the new ASWT interns arrived at the Shumla campus, the weather conditions were highly favorable to finally build our long awaited experimental earth ovenAfter gathering enough firewood (fuel), lechuguilla and sotol (food), and close to 100 kilograms of limestone clasts from the immediate surroundings, the crew was ready to begin constructing the earth oven.

We began by digging a pit close to a meter and a half in diameter, and a half a meter in depth. The firewood (hand-gathered deadwood) was then stacked in a conical pyre (similar to a tepee), and the limestone rocks were strategically placed within the cone of firewood.

The crew agreed that it was best to light the fire the traditional Lower Pecos way, so Park Archaeologist Jack Johnson of Amistad National Recreation Area (US National Park Service) used the bloom stalk of a sotol plant to start a friction fire. In under 2 minutes, Jack had the fire blazing under the stars (for a time-lapse of the earth oven fire, watch this video by Jack Johnson: https://www.facebook.com/video.php?v=10152425529847134&pnref=story).

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The blazing conical pyre of firewood and limestone rock in shorty after it was fired.

 

After the fire burned down to embers and the rocks were glowing red hot in the bottom of the pit, the crew and several student volunteers from Texas State University began lining the the pit with prickly pear pads – the pads serve as a lower layer of packing material that helps to retain the moist heat needed to bake the food at a low temperature (ca. 100 C) for an extended period of time (typically 36 -48 hours.)

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Placing the first layer of packing material (prickly pear pads) ontop of the hot limestone rock.

 

Once the prickly pear was placed, it was time to throw in the food we collected. Lechuguilla and sotol hearts (3 each) were placed in the center of the pit on top of the prickly pear and covered again with more packing material.

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Laying the food (Sotol and lechuguilla) on top of the packing material.

 

After the remaining packing material was thrown over the food, we began to cover and cap the pit with dirt; this cap of soil insulates and holds in the steamy heat released from the rocks and suffocates the fire allowing no combustion. Now it was time to wait for our plants to bake and hope our hard labor would deliver some tasty results!

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Capping the earth oven with soil.

 

 

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Charles packing down the cap of soil to ensure no heat escapes.

 

Dinner is Served:

On the evening of January 13th, two days after we capped and sealed our earth oven, the crew returned to taste the baked desert succulents that were slow cooked over the last 48 hours. While digging the bulbs out of the pit, we noticed how the soil was still warm from the heated rocks below. The baked lechuguilla and sotol had a turned a caramelized color and had an aroma that smelled similar to a smokey artichoke.

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The baked bulbs of sotol and lechuguilla.

 

The palatability  of these baked plants sent mixed expressions across the faces of our crew, some of who enjoyed the flavor and some who didn’t.

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Tasting our baked food for the first time. The faces say it all.

 

Learning from Earth Ovens:

A great variety of scientific information potentially can be obtained from the experimental construction of earth ovens.  One aspect of earth oven use ASWT is particularly interested in is understanding the rate at which limestone rock breaks down through repeated use in earth ovens. The layer of heated limestone rocks forming the bed of an earth oven serves as a thermal storage or heating element that slowly cooks the food. During the firing process, the limestone rocks begin to break apart from the intense heat that they are exposed to (over 500 C).  Through reuse, thermal cycling–from cold to hot to cold again– causes the rocks to continue to fracture into ever smaller pieces.  Solid rocks with few flaws typically last longer than naturally fractured rocks and those with thin spots. Once the rocks becomes too small to retain heat, they are no longer effective thermal storage devices and they are discarded and tossed into what will become a debris ring around the oven pit, eventually qualifying as a burned rock midden. If we can track and measure a known mass of limestone rock (e.g., 100 kilograms/220 pounds) as it continuously breaks down into smaller rocks from heat and re-used in new earth ovens, we could then to apply this experimental rock-size attribute data to the fire-cracked rock (FCR) that we find in such profusion in the archaeological ground. In other words, this experimental use of earth ovens can potentially allow us to more accurately measure the amount of earth oven cooking that took place in Eagle Cave and other rockshelters and open sites in the region.

Eagle Cave’s Feature No. 8:

Last week, Emily and Larsen uncovered what we think is an intact earth oven heating element in their excavation unit. To a trained eye, this earth oven feature was characteristically textbook in its makeup. Many of the limestone rocks were inclined at the base of the pit and the soil that surrounded these fire-cracked rocks was heavily organic, ashy, and rich with dime-size charcoal chunks. It even appeared as if there had been a different soil that was used to cap this earth oven once long ago.

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3D model (plan view) of feature 8 in Eagle Cave. Notice the dense cluster of fire cracked rock and black/grey charcoal rich soil.

 

 

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Plan and profile view of feature 8 in Eagle Cave.

 

With intact, well-preserved finds such as Feature 8, we have the ability to obtain radiocarbon dates that can help us determine when this oven was used.  Furthermore, we can sieve the collected soil from that earth oven feature and, with the help of our collaborating archaeobotanists, identify the charred plant remains that were being processed by the people who lived in Eagle Cave. What we cannot do is accurately estimate how many times this earth oven was re-used. Was Feature 8 a one-time earth oven event? Or was it the last of series of earth ovens that had been built and re-used in this very spot using the same rocks? These are some of the questions that ASWT would like to address in our ongoing research. Through these initial tests with EEO No.1 and other experimental earth ovens to follow, we believe that the data to answer these questions could come to light.

ASWT Experimental Earth Oven (EEO) No. 1

After enjoying the success of our first experimental earth oven, we returned  a week later to dig out all the rocks from EEO No. 1.  We used 11 rocks larger than 15 cm in maximum dimension in the oven (99 kg or ~220 lbs of total), and we were able to recover all the rock that was used.  Most of the rocks survived the fire, but as you can see from the photograph below, some of the rock broke into smaller fragments.

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The rock size sorted fire cracked limestone, post earth oven firing.

Once all the rocks were pulled out of the oven, we divided the rocks into four size categories: <7.5 cm in maximum dimension, between 7.5-11 cm, 11-15 cm, and >15 cm in maximum dimension.  We used the same familiar size categories we use in the recording procedure we call “Rock Sort” which allows us to quantify the rocks from each excavation unit-layer.  The smallest two size classes (<7.5cm and 7.5-11cm) contain rocks that are too small to be effectively used again as rocks for the heating element.  After counting and weighing all the rocks in each size class, almost all of our rock (93 out of 99 kg) survived to be used again.

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Weighing the fire cracked limestone rock.

 

Likely during our next session, all the useable limestone rock from ASWT EEO No. 1 will be re-used in another experimental earth oven event.  After the second firing (ASWT EEO N0. 2.) we will once again recover all the rocks, sort the rocks into different size categories, and weight all of them.  We will continue to re-use the same rocks until the rocks all become too small (<3.5 inches) to effectively retain heat anymore. The more times we “burn” the rocks, the more data we will collect to further our goal.  We anticipate great data and results to come!

 

Earth Oven: Searching for the Trifecta

by Jake Sullivan and Brooke Bonorden

Let me begin by explaining what an earth oven is. An earth oven is a cooking technology that has been widely used in the Lower Pecos for thousands of years. To create an earth oven, a pit is dug into the ground and a fire is built. Large stones are placed amongst the flames; these stones retain the fire’s heat and become the oven’s heating element long after the fire has died out. Next, a layer of packing material is laid across the hot stones in order to insulate the food from direct heat and provide moisture. Prickly pear pads work great for this and can be found in abundance in the Lower Pecos. The food load, the trimmed hearts of the desert succulents sotol and lechuguilla, is placed on top of the packing material followed by another layer of packing material. The oven is then capped by a thick layer of earth to prevent precious steam heat from escaping. After cooking for at least 36 hours the food is ready to be unearthed and consumed.

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Processing sotol for an experimental earth oven.

The baking process turns the complex carbohydrates within the plants into sugar. These plants also contain a chemical called saponin, which is inedible in its raw form but is rendered harmless by the cooking process. I can tell you from experience that baked sotol doesn’t always taste good, but it is a reliable food source in a harsh and highly variable environment.

As part of the ENC project, one of the research topics we are interested in is calculating how much earth oven processing occurred at different sites, i.e. how many times each earth oven locale was used. Fire-cracked rock (FCR) is the most common remnant of an earth oven cooking facility found in an archaeological context. In the field we have been sizing, counting, and weighing the FCR that we find in each layer of our excavation units. What we find most often, and what makes up the majority of the enormous talus slopes in front of the shelters, are FCR that have been discarded after multiple heating events and are now too small to store heat efficiently. However, in order to find out how much earth oven processing has occurred we need to do more than just count and weigh the burned rock coming out of our units. We are planning to do this by trying our hand at some Experimental Archaeology.

One of the challenges for archaeologists is understanding how the things you find in the ground are related to human activity—especially when it comes to burned rocks.  So, we carry out different experimental archaeology projects to help us figure out what burned rocks in the ground might represent. Collectively, we have built many earth ovens to demonstrate the plant baking process from start to finish. However, beyond demonstrating how local edibles were processed by those who occupied the rockshelters we work in, we did not collect any real scientific data to help us answer questions related to earth oven processing.  So, we are planning a series of long-term experiments by creating our own earth ovens. We hope to document the number of plant baking episodes necessary to significantly reduce the size of our heating elements (rocks) to the size of the FCR that we are finding in burned-rock middens (BRM) throughout the canyon.

On Thursday the ENC crew searched the property surrounding the Shumla campus for a new site for our upcoming experimental earth oven. When seeking out the new oven location we tried to keep in mind the qualities that would have appealed the natives who were using this cooking technology for their survival. The vast majority of optimal locations we saw while traipsing through the always-thorny local shrubbery were already occupied by evidence of prehistoric plant baking – fire-cracked rocks. What makes a location optimal is its proximity to the trifecta: fuel, food, and dirt. Native peoples would have tried to find a location that was relatively close to all the fuel, food, and dirt they needed to construct and fill the oven so they wouldn’t have to expend extra energy hauling in supplies. Eventually we found a pristine location untainted by archaeological evidence. 

In anticipation of building our first earth ovens in the new locale, our first task is to collect phosphate samples at the recommendation of our geoarchaeologist colleague Ken Lawrence.  Phosphorous (or P) analysis looks at the phosphate that accumulates in sediment by many aspects of human activity. What’s great about phosphorous is that it decays very slowly through geologic time, so it’s a reliable element for targeted study. Our goal in using this method is to analyze how quickly and at what levels phosphate will accumulate in sediment that has been manipulated by plant processing and baking. To accomplish this we will be taking initial baseline samples at the oven location, and then Ken will come back and collect more once we have started processing.  This is important to archaeologists because it gives us another way to interpret the intensity of the plant processing that occurred at local sites. By understanding how much earth oven processing occurred, we will be able to compare how many times different sites were used, and gain a better understanding of how people moved across the LP landscape.

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We can’t believe how good it tastes!

 In a few weeks we will tap the trifecta and start building ovens and monitoring the cracking rocks.  We will also be following a pattern that native peoples must have relied on – in the winter, lechuguilla and sotol are among the few potentially edible plants that can be harvested.