Finding Microwear Patterns on Stone Tools: Marilyn Shoberg, TARL Microwear Analyst

Featured image: Microwear analyst Marilyn Shoberg examines a stone tool under a microscope in the TARL laboratory. She typically makes observations at magnifications ranging from 50X to 500X and captures potentially diagnostic wear traces with a digital Moticam camera.

by Marilyn Shoberg

After receiving my MA in Anthropology from UT-Austin,  I joined the Gault Project at TARL in 2000 and began doing microwear analysis, looking at experimental tools and archeological tools from the Gault Site. Some of the stone artifacts in an archeological assemblage are formal tools that have recognizable shapes such as projectile points, bifaces, or endscrapers. Many more artifacts appear to have been used, however, and unless we look at them under the microscope we can only guess at what their function may have been.

When a stone tool is used the edge is gradually worn away by the loss of flakes and abrasion, and the surface is modified by contact with the worked material so that it appears shiny or polished.  Microwear analysis is a systematic process of recording wear traces such as edge flaking, the surface characteristics of polish, and the orientation of striations on a stone tool in order to determine how that tool was used.

The research microscope used at TARL for this analysis is an Olympus BH2 reflected light microscope with Nomarski optics. Observations are made at magnifications from 50X to 500X.  Images of potentially diagnostic wear traces are captured with a digital Moticam camera.

Microwear analysts learn how to identify the various attributes of wear traces by looking at experimental tools used in many different tasks on a wide variety of materials.  It is absolutely essential for every analyst to do experiments and to acquire a reference collection of tools used in tasks relevant to prehistoric human behavior.  The comparative collection of experimental tools we have at TARL is a terrific asset for analysis and teaching.  It has grown from the work of many former students here at UT, archaeologists and friends of archaeology.  The collection includes tools used on plant materials, several kinds of wood, bone, antler, elephant ivory, hide, and butchering a variety of animals.

Patterns of wear on replicated stone tools used for woodworking are shown at a magnification of 500X. The three tools--an adze and two flakes--were crafted by a modern knapper and used for different tasks on different types of wood. Experimental tools such as these provide a comparative baseline for discerning microwear patterns on ancient tools, determining how they might have been used, and on what materials.
Patterns of wear on replicated stone tools used for woodworking are shown at a magnification of 500X. The three tools–an adze and two flakes–were crafted by a modern knapper and used for different tasks on different types of wood. Experimental tools such as these provide a comparative baseline for discerning microwear patterns on ancient tools, determining how they might have been used, and on what materials.

 

In addition to a large number of Clovis tools from the Gault Site, I have analyzed artifacts from a number of CRM projects in Texas, and sites in Arizona, Illinois, New Hampshire, Kentucky and Belize.

In archaeology we attempt to understand past human behavior from material culture, however only a very small fraction of that material culture survives.  The things that people made from perishable organic materials such as plants, wood, bone, and skin are for the most part missing from the archaeological record.  The fascinating aspect of microwear analysis is that the tools used in the manufacture of the “missing majority” of that perishable material culture provide clues to the kinds of things people were making at particular places.

Among the most interesting tools I have looked at are a small Clovis age flake used to incise bone, tools used to pierce animal skin, perhaps in the manufacture of clothing or shelter, and small prismatic blade fragments used in fine cutting or scraping tasks on grass, reed and wood.  Sometimes you find an example of a recycled tool like a used-up projectile point re-purposed as a scraper or abrader on animal skin.

You are welcome to contact me to learn more about the research I conduct and to discuss my availability to contribute to projects under contract.  My contact information is below:

Marilyn Shoberg

Microwear Analyst

Texas Archeological Research Laboratory

The University of Texas at Austin

1 University Station R7500​

Austin, Texas 78712

mbshoberg@mail.utexas.edu

 

A Masterpiece in Stone

Featured image:  This exceptionally well made corner-tang knife measures almost a foot in length and just over a third of an inch in thickness.  Because it derived from a burial context and appears to be unused, it almost certainly was a “ritual” or symbolic object, reflecting the special status of the individual with whom it was buried.  TARL Collections; photo by Laura  Nightengale.

by Susan Dial

More than 1500 years ago, an expert craftsman fashioned this unusual corner tang biface with an extraordinarily long, curved blade.  Based on the color and fine-grained texture  of the stone, the material he chose for this piece likely derived from the Georgetown  area in central Texas.  And based on the over-sized  proportions and lack of wear along the blade edges or other evident signs of use, the piece had not been  intended for utilitarian purposes.

In 1974, excavators from The University of Texas at Austin uncovered the biface along with numerous other items—including a second corner tang biface and shell ornaments—from the burial of a young woman in a prehistoric cemetery in Austin County, Texas.   Known as the Ernest Witte site (41AU36), the cemetery contained more than 250 burials, reflecting approximately 3000 years of use.  The burial group from which the biface was recovered dates to Late Archaic times, ca.  650 B.C. to A.D. 450, and was notable for evidence of violence within the remains (at least five individuals died from dart point wounds).   In addition, several artifacts from the same burial group were made from “exotic”, or nonlocal, materials, indicating the people were involved in a long-range trade network or “import-export” system during the Late Archaic.  For example, several boatstones (likely atlatl weights) and a gorget were made of stone from the Ouachita Mountains of Arkansas, hundreds of miles distant.

Corner tang knives are a distinctive artifact form, typically characterized by an off-center placement of the tang, or haft element, but varying considerably in size and blade shape. Edge wear on some suggests hafting for use as a cutting implement; others have been worn down through use and reworked into drills. Thought to originate in central  Texas  (based on numbers of recorded specimens in a 1930s study by J. T. Patterson), more recent tallies indicate their distribution extends as far north as Wyoming, although generally confined to the Plains.

The specimen from the Ernest Witte site is without question one of the finest and largest known examples of the corner tang type.  Measuring 28.8 cm in length and 5.1 cm in width, it is exceptionally well thinned, with maximum thickness of less than one centimeter.  The remarkable proportions of this artifact—its length and flatness—suggested to  Site Archeologist Grant Hall that the piece was made on a large chert slab which had been reduced to form a blank, rather than from a large flake.

Because of its context and because it appears unused, we can conclude that this grave offering carried special significance, a ritual or symbolic function. Indeed its large blade size relative to the diminutive stem almost certainly would result in a break if the tool were hafted and used for cutting, skinning, or some other process. Smaller corner tang bifaces found throughout central Texas show evidence of use such as worn or beveled edges and fractures.

Although very rare, large corner tang bifaces have been recovered from burials in other south Texas cemetery sites including the Morhiss Mound site in Victoria County and the Silo site  (41KA102) in Karnes County.

At Silo, three corner tang artifacts were found with the burial of a child who was interred beneath an adult male.  Like the Ernest Witte corner tang specimens, those from the Silo site appear to be unused.  Archeologists Cory Broehm and Troy Lovata wrote of the Silo Site items:   “The combination of quality, size, and context of these artifacts is exceptionally rare. These pristine artifacts suggest the child was held in very high esteem.”  Two additional specimens were associated with the burial of an adult male at the site.

It is interesting that at both the Silo site and the Ernest Witte cemetery, some of the females were interred face down in the grave.  Indeed, this rather unusual mode of burial was almost exclusively reserved for females, with only one male in Group 1 and one in Group 2 (the Late Archaic) interred in this fashion at Ernest Witte.  The exceptionally crafted corner tang biface from that site, shown at the top of the page, was placed in the grave of a woman who had been interred face down.  While we cannot know what these different practices and grave offerings meant to the groups who buried their dead at these and other south Texas cemetery sites, they are important reminders of the rich complexities of hunter-gatherer mortuary customs.

 

For more information:

Records and collections from the Ernest Witte site are curated at TARL and are reported in Allens Creek: A Study in the Cultural Prehistory of the Lower Brazos River Valley by Grant D. Hall (Texas Archeological Survey Research Report No. 61, The University of Texas at Austin, 1981).

Records and collections from the Silo site are curated at TARL and are reported by Troy Lovata in Archaeological Investigations at the Silo Site (41KA102), a Prehistoric Cemetery in Karnes County, Texas. (Unpublished M.A. thesis, Department of Anthropology, University of Texas at Austin, 1997).

See also:

Broehm, Cory J. and Troy R. Lovata

2004 Five Corner Tang Bifaces from the Silo Site, 41KA102, a Late Archaic Mortuary site in South Texas. Plains Anthropologist 49(189):59-77.

Patterson, J. T.

1936 The Corner-Tang Flint Artifacts of Texas  by J. T. Patterson (University of Texas Bulletin No. 3618, Anthropological papers, Vol. 1, No. 4); Corner-Tang Stone Artifacts of the Plains.

 

Corner-tang bifaces from the burial of a child at the Late Archaic Silo site in south Texas.  Although not as large as the Ernest Witte specimen, they are of similar quality. TARL Collections.
Corner-tang bifaces from the burial of a child at the Late Archaic Silo site in south Texas. Although not as large as the Ernest Witte specimen, they are of similar quality. TARL Archives.

 

Small corner-tang artifacts with edge-wear and other signs of use. The tools likely were used for a variety of tasks. TARL Collections.
Small corner-tang artifacts with edge-wear and other signs of use. The tools likely were used for a variety of tasks. TARL Collections.

 

 

Archeomalacology

by Ken Brown

Archeomalacology is the study of mollusks in archeological contexts. Strictly speaking, this might include marine bivalves, marine snails, freshwater mussels, and various kinds of inland snails. In practice, though, I work only with snails (terrestrial, amphibious, and aquatic) from continental settings, along with some other kinds of very small invertebrate organisms that are sometimes recovered in snail sampling (pea clams, fingernail clams, and freshwater limpets).

There are two reasons why archeologists might want to commission studies of snails from archeological sites:

1) Snails are useful paleoenvironmental indicators.

2) In Central and South Texas, snails of the genus Rabdotus were a conspicuous food item beginning in the Early Archaic and perhaps peaking in exploitation in the Late Archaic.

Furthermore, snails can be used as a source of organic material for radiocarbon assay or epimerization studies, and have also been used for carbon and oxygen isotope studies.

Although to most archeologists, “snail” and “Rabdotus” are synonymous, in reality there are many native Texas land and amphibious species and perhaps as many as 41 aquatic species (although DNA studies are collapsing this number). Kathryn Perez estimates that there are as many as 185 contemporary and extirpated terrestrial species and subspecies, although I am skeptical that all these of these species reports are valid (many reports probably date from decades ago, when taxonomic splitting was rampant, and the real number of Texas natives is probably significantly lower). There are also a few species that have been extirpated since the Pleistocene, and around a dozen or so invasive Eurasian land or aquatic species. The native terrestrial species differ widely in habitat preference and body size, from the tiny Carychium mexicanum (adult shell height, 1.7-2.0 mm) to Rabdotus alternatus (adult shell height, up to 4.3 cm). In archeological sites where habitats were favorable and proper sampling is done, generally about two to three dozen taxa can be expected. In Texas, the Lubbock Lake site holds the record for diversity, with just under four dozen taxa.

Here are two of the most common micro-sized terrestrial snail species in Texas (these examples are from Berger Bluff, in Goliad County). Neither will be captured in quarter-inch mesh.

Image: Here are two of the most common micro-sized terrestrial snail species in Texas (these examples are from Berger Bluff, in Goliad County). Neither will be captured in quarter-inch mesh.  Image courtesy of Ken Brown.

To read more about archeomalacology and Ken Brown’s work, go here:  https://sites.utexas.edu/tarl/projects-research/

 

Explore UT 2015: A Success!

by TARL Staff

Thanks to the efforts of our very own Rosario Casarez, TARL’s involvement with UT’s educational ‘open house’ program was a great success this past Saturday!  Despite the rather chilly and overcast beginning to the day downtown on the main campus, the sun eventually put in an appearance and warmed us up as we manned our tables, answered questions, warded off loaded paintbrushes, made corn husk dolls and handed out information about archeology in Texas.  Arriving early, we put up our tables and mingled with the dedicated anthropology graduate students and then ferreted out the nearest Starbucks (1st floor of the SAC!) to properly fortify ourselves for the morning.

Jonathan Jarvis, our Associate Director, and Susan Dial, editor and project manager of Texas Beyond History, both presented talks in a classroom on the first floor of the CLA building.

As taken from the official Explore UT 2015 schedule: Archaeologist Jonathan Jarvis describes how archaeologists use historic maps and discusses the role of accurate mapping in archaeology today. See how using geospatial tools to locate man-made features below the earth’s surface can help future research.  

And Susan’s talk was a “Detectives into the Past” presentation with Dr. Dirt in which she focused on reconstructing the diet of ancient Texans based on the study of coprolites (preserved human fecal remains).

To get a sense of the kind of turn out that we were a part of at Explore UT please check out this brief video, provided courtesy of UT anthropology graduate student Luisa Aebersold (who also provided the featured image for this post!), on her Twitter feed:  https://twitter.com/luisaaebersold/media

First, there was ‘getting organized:’

ExploreUT2015_settingup_2
Brain and Jonathan considering the myriad options for banner directions (or they were pointing at me to do something and I conveniently didn’t hear).

 

Steven and Marybeth set up the artifact table.
Steven and Marybeth set up the artifact table, displaying the delight all archeologists exhibit when handling Texas material culture in combination with venti lattes.

 

Elizabeth and Jean setting up the materials they will need to create the very popular corn husk dolls.  Susan was attempting to hide in the background until her first presentation at 11am.
Elizabeth and Jean setting up the materials they will need to create the very popular corn husk doll-making activity. Susan was attempting to hide in the background until her first presentation at 11am.  Susan, when you want to hide from people, DON’T wear red!

 

Marybeth was practicing her 'artifact pop-quiz' skills on an unsuspecting Steven in preparation for the tons of children who were glad that there were actually objects they could touch and hold.
Marybeth was practicing her ‘artifact pop-quiz’ skills on an unsuspecting Steven in preparation for the tons of children who were glad that there were actually objects they could touch and hold.

 

Susan made sure that Texas Beyond History was properly represented at this year's Explore UT with lots of handouts and informational material.  Her bookmarks for TBH are always popular!
Susan made sure that Texas Beyond History was properly represented at this year’s Explore UT with lots of handouts and informational material. Her bookmarks for TBH are always popular!

 

...the good news is that we managed to NOT close-line anyone walking  by the TARL banner.
…the good news is that we managed to NOT close-line anyone walking by the TARL banner.

 

Ph.D. candidate Stacy Drake explaining what bones can tell scientists about the people from the past and how they lived.
Ph.D. candidate Stacy Drake explaining what bones can tell scientists about the people from the past and how they lived.  Image provided courtesy of UT anthropology graduate student Luisa Aebersold.

 

Kids had the opportunity to try their hand at grinding dried corn using a mano and metate...and realized  very quickly how much work went into preparing food before McDonald's arrived on the scene.
Kids had the opportunity to try their hand at grinding dried corn using a mano and metate…and realized very quickly how much work went into preparing food before McDonald’s arrived on the scene.  Image provided courtesy of UT anthropology graduate student Luisa Aebersold.

 

As always, Jean was extremely popular at her table where she showed children (and adults!) how to make corn husk dolls.
As always, Jean was extremely popular at her table where she showed children (and adults!) how to make corn husk dolls.  Image provided courtesy of UT anthropology graduate student Luisa Aebersold.

 

Ph.D. candidate Debora Trein working at the table where kids had the chance to write their name in Egyptian hieroglyphs.  We were fortunate to have the opportunity to work side-by-side with the graduate students who have been ensuring a anthropology presence at Explore UT for the last several years.
Ph.D. candidate Debora Trein working at the table where kids had the chance to write their name in Egyptian hieroglyphs. We were fortunate to have the opportunity to work side-by-side with the graduate students who have been ensuring an ‘anthropology presence’ at Explore UT for the last several years.  Image provided courtesy of UT anthropology graduate student Luisa Aebersold.

 

This is a wonderful image of children trying their hand at mending pottery.  It was impressive to watch how focused some of the children would become trying to fit the sherds together to reconstruct parts of the vessels.
This is a wonderful image of children trying their hand at mending pottery. It was impressive to watch how focused some of the children would become trying to fit the sherds together to reconstruct parts of the vessels.  Image provided courtesy of UT anthropology graduate student Luisa Aebersold.

 

Rosario bravely manned the rock art painting table, ducking loaded paint brushes and trying to prevent all of the paint from turning into various shades of brown. Image provided courtesy of UT anthropology graduate student Luisa Aebersold.

 

Rosario had this to say about her very popular activity this year: “The rock art activity consisted of several images of Texas rock art printed on card stock that visitors could paint. The only colors I made available for painting were colors used by Native Americans. So the colors were red, black and as close to ochre as I could mix. They also used white… pigments were made from berries, roots, stones, etc. and I was asked throughout the day if I had made my own paint. I will say no berries were harmed for this activity, but there’s this wonderful stuff called tempera paint! The most popular image the children wanted to paint was the bird, I actually ran out of them. I don’t know what it is about this bird from 41RE14 in Real Co., but it is well liked.”

The image from the site that was so popular?

Bird

 

There was also a tremendous amount of excitement about TxDOT staff archeologist Chris Ringstaff being in attendance to demonstrate flint knapping for the people who attended.  Chris was wonderful at not only demonstrating the various techniques that would have been used by the prehistoric knappers who inhabited Texas, he did a great job of explaining why they did what they did: why they chose the stone they chose, used the tools they used and worked the various kinds of flakes in various ways.  His demonstration was well-attended and all of us took an opportunity to stop and watch this professional archeologist and researcher explain his craft.

 

Chris Ringstaff explaining the use of atlatls (spear throwers).
Chris Ringstaff explaining the use of atlatls (spear throwers).

 

Chris showing the shaft of a "dart" and why selection was so critical to the effectiveness of this tool.
Chris showing the shaft of a “dart” and why selection was so critical to the effectiveness of this tool.

 

Chris shows everyone what the raw materials used were, demonstrating with a  piece of chert.
Chris shows everyone what the raw materials used were, demonstrating with a piece of chert.

 

Chris displaying for attendees the different types of "billets" that would have been used for knapping (parts of the knapper's kit).  They include deer antler "billets" of various sizes for soft percussion and fist-sized "hammer stones" for hard percussion work.
Chris displaying for attendees the different types of “billets” that would have been used for knapping (parts of the knapper’s kit). They include deer antler “billets” of various sizes for soft percussion and fist-sized “hammer stones” for hard percussion work.

 

In this image Chris is preparing a platform for flake removal.
In this image Chris is preparing a platform for flake removal.

 

The same way the knapping would have been practiced by the early inhabitants of Texas, Chris gets to work without the modern comforts of chairs, tables and full gloves.
The same way the knapping would have been practiced by the early inhabitants of Texas, Chris gets to work without the modern comforts of chairs, tables and full gloves.

 

An example of the various kinds of projectile points that would have been made by the prehistoric inhabitants of Texas.  Chris was able to help people to see and learn for themselves the historic, cultural and scientific value of prehistoric material culture, why it was effective and how it evolved.
An example of the various kinds of projectile points that would have been made by the prehistoric inhabitants of Texas. Chris was able to help people to see and learn for themselves the historic, cultural and scientific value of prehistoric material culture, why it was effective and how it evolved.

 

This year’s Explore UT was an opportunity for those of us who work at TARL to make what we do accessible to the public, especially as pertains to using archeology to teach science and social studies to children.  Archeology offers tangible, understandable lessons about the evolution of man, his culture and his technology and TARL staff look forward to other opportunities to work with schools, educators and students to help them appreciate and utilize the wealth of material culture that, in many ways, originated in their own backyards.  Thank you to everyone who came out to contribute and who  participated in making this an opportunity for TARL to renew its ties to the anthropology department and main campus.  We look forward to many more years of educational contributions.

 

ExploreUT2015_settingup_11

 

 

Student Project Update: Truc Nguyen

by Truc Nguyen

The past two weeks involved hands on work that I was able to do on the rehousing project of our naturally preserved mummy. Working with cardboard boxes, duct tape, and other tools, I was able to come up with my first rough idea for both the outer box and inner sled. Upon further work, both Kerri and I decided that an additional inner sled would be needed.  Hope to keep you all updated as we make more progress!

 

Truc has been busy constructing models of the long-term mummy housing.  She is experimenting with different types of boards, tapes and designs to better understand how viable her design will be.  The materials that she will be using in the design of her final project will be archival, chemically inert and offer the rigid support needed to protect such a delicately preserved individual.
Truc has been busy constructing models of the long-term mummy housing. She is experimenting with different types of boards, tapes and designs to better understand how viable her design will be. The materials that she will be using in the design of her final project will be archival, chemically inert and offer the rigid support needed to protect such a delicately preserved individual.

 

Once she decided on a drop-front outer box that will provide the rigid protection necessary for moving the mummy she focused on a desgning an interior sled with handles.  This will allow researchers to access the remains by untying the stays and dropping the front of the box and then sliding forward the interior sled.
Once she decided on a drop-front outer box that will provide the rigid protection necessary for moving the mummy she focused on a designing an interior sled with handles. This will allow researchers to access the remains by untying the stays and dropping the front of the box and then sliding forward the interior sled.

 

Truc's project is intended to improve the stability, protection and access of one of our most sensitive sets of remains.  Designed much like a set of Russian nesting dolls, the various envelopes will provide 1. the rigidity necessary to move the box when necessary, 2. the ability to access approximately 160 degrees of the remains, and ultimately 3. 180 degrees with the insertion of a flat, reinforced platform with custom-contoured ethafoam supports that will prevent the mummy from turning or leaning.
Truc’s project is intended to improve the stability, protection and access of one of our most sensitive sets of remains. Designed much like a set of Russian nesting dolls, the various envelopes will provide 1. the rigidity necessary to move the box when necessary, 2. the ability to access approximately 160 degrees of the remains, and ultimately 3. 180 degrees with the insertion of a flat, reinforced platform with custom-contoured ethafoam supports that will prevent the mummy from turning or leaning.

 

For information on Truc’s project:  RehousingTARLMummies

Check back later in the week as Truc continues to design and engineer protective long-term housing for this delicate set of remains as she continues her research into best practice for creating stable, preservation micro-environments for organic objects.

 

 

Of Snips and Snails

by Susan Dial

Sometimes even the smallest of creatures can provide big insights.  Dr.  Ken Brown, an archeologist and TARL Research Affiliate, has been on the trail of snails for decades.  From these seemingly inconsequential mollusks, a wealth of data about past environments at archeological sites can be gleaned.   Simply put, different species of snails can thrive in different environmental conditions.  By determining which species were present at a given time, he can reconstruct what the climatic conditions were like over time.  His observation of snails (species, habitat requirements, species densities and distributions, etc) allow him to contribute invaluable insight into site formation and transformation over time, evidence of bioturbation, possible signs of cultural utilization, and especially paleo-environmental reconstruction.

The processes involved in snail analysis is painstaking and often tedious, involving screening sediment samples through a series of increasingly fine-grained mesh, picking out the shells, sorting by size, and finally identifying them.  Good eyesight is a must for this job: some snails in his samples are less than a millimeter across, and specimen storage is in gel caps, not plastic bags.  For archeologists, however, this sort of information can be invaluable—and often the only available indicator of past environments.

Ken’s research interests are hardly limited to snails, however. He also is a specialist in prehistoric wooden artifacts, having studied (and identified) dozens of the snares, traps, curved sticks, dart shafts and other enigmatic items from TARL’s perishable collections.  His detailed drawings, descriptions, photos and lab notes of these remarkable artifacts now fill very large ring- binders—the makings of a publication long awaited by other archeologists.

Ken’s interest in archeology can be traced back to his teen years participating in Texas Archeological Society field schools. He has been at it ever since.  Awarded a Ph.D. from the University of Texas at Austin, he has worked in the field for nearly 40 years and mostly at sites in Texas, but also in New Mexico, Colorado, Oklahoma, Arkansas, Illinois and New York.   Ken’s dissertation on the Berger Bluff site in Victoria County provides unique insight into the Late Pleistocene and Early Holocene climatic history of the coastal plains of Texas. For that site—and many of the others he’s worked on—he did multiple types of analyses, analyzing not just mollusks,  but myriad other fauna, lithics, etc.

Ken also has contributed substantive content to Texas Beyond History, including the McFaddin Beach exhibit (“This Site Is All Washed Up!”) http://www.texasbeyondhistory.net/mcfaddin/index.html and a “mini-exhibit” on Berger Bluff http://www.texasbeyondhistory.net/st-plains/images/ap5.html. In the past several years, he has also served as a TBH reviewer; his broad expertise and eagle eye as an editor have been greatly appreciated.  His current work is focused on a project at the Genevieve Lykes Duncan site in Brewster County, one of only a few sites with Paleoindian-age deposits in the Trans Pecos.

In subsequent blog posts, Ken will share some of what he has learned about snails… and many other subjects, we hope!