The Mystery of the Guangala Obsidian: A Functional Examination Through Experimental Archaeology

… Thousands of years later …

Nature of Experiment Choose artifacts Choose artifacts Create replicas using experimental methods Create replicas using experimental methods Use replicas on various contact materials Use replicas on various contact materials Use microscopy to examine damage on artifacts and replicas Use microscopy to examine damage on artifacts and replicas Compare replicas to artifacts Compare replicas to artifacts Draw conclusions about function of the obsidian blades Draw conclusions about function of the obsidian blades

History of the Guangala ● Culture flourished from 100 BC-800 AD Lived in Southern Coastal Ecuador Artifacts and descendant cultures provide clues Many questions unanswered

Culture and Society Religion: animistic Religion: animistic Beauty: tattooing, body painting, piercing Beauty: tattooing, body painting, piercing Clothing: cotton Clothing: cotton

Lifestyle Revealed Through Artifacts Grindstone  Agriculture Grindstone  Agriculture Fish hooks  Fishing Fish hooks  Fishing Foreign resources  Trade Foreign resources  Trade Obsidian  ??? Obsidian  ???

Flintknapping Process of manufacturing stone tools Process of manufacturing stone tools –Works because brittle stone fractures with pressure Obsidian—natural glass material that forms sharp edges Obsidian—natural glass material that forms sharp edges

Materials SoftMediumHard SkinGrassWoodCartilageBoneShell

SEM and Light Microscopes Light microscope—reflects and refracts light Light microscope—reflects and refracts light - shows greater amount of object SEM—shoots electron beams SEM—shoots electron beams - higher resolution and magnification - Preparation may inhibit analysis

The Archaeology

What Makes a Good Match? Flake scars Flake scars Edges: peaks, crevices, etc. Edges: peaks, crevices, etc. Other: Striations, Pitting, etc. Other: Striations, Pitting, etc.

Meet the Artifacts!

Artifact 1 SEM x100 Flake Scarring: 1 large flake scar and smaller irregular flake scars, shallow scars Flake Scarring: 1 large flake scar and smaller irregular flake scars, shallow scars Edges: deep crevices with rounded/dull fracture peaks, shallow ridges Edges: deep crevices with rounded/dull fracture peaks, shallow ridges Other: striations Other: striations2 3 1

Artifact 2 SEM x1000 Flake Scarring: shallow but well-defined flake scars Flake Scarring: shallow but well-defined flake scars Edges: jagged edges, rounded peaks between flake scars Edges: jagged edges, rounded peaks between flake scars Other: deep striations radiating from flake scars, some crumbling Other: deep striations radiating from flake scars, some crumbling3 1 2

Artifact 3 SEM x500 Flake Scarring: shallow micro-scars (when magnified), extremely small, irregular distribution Flake Scarring: shallow micro-scars (when magnified), extremely small, irregular distribution Edge: irregular, jagged damage, edges worn down with no distinct peaks Edge: irregular, jagged damage, edges worn down with no distinct peaks Other: percussion ripples, striations Other: percussion ripples, striations3 1 2

Meet the Replicas!

Replica 1: Wood SEM x500 Flake Scarring: micro-scars visible only under SEM Flake Scarring: micro-scars visible only under SEM Edge: minor, irregular shallow chipping with small, rounded peaks Edge: minor, irregular shallow chipping with small, rounded peaks Other: frequent, irregular surface pitting Other: frequent, irregular surface pitting1 2 3

Replica 2: Grass on Grindstone SEM x2000 Flake Scarring: micro-scars visible only under SEM Flake Scarring: micro-scars visible only under SEM Edges: rounded off dull edges without peaks Edges: rounded off dull edges without peaks Other: none Other: none3 1 2

Replica 3: Cartilage SEM x2000 SEM x360 Flake Scarring: well-defined flake scars, vary from wide and smooth to deep and narrow Flake Scarring: well-defined flake scars, vary from wide and smooth to deep and narrow Edges: very deep crevices with steep fracture peaks, shallow jagged edge fractures with sharp peaks Edges: very deep crevices with steep fracture peaks, shallow jagged edge fractures with sharp peaks Other: damage striations Other: damage striations341 2

Replica 4: Skin Flake Scarring: small, shallow irregular flake scars Flake Scarring: small, shallow irregular flake scars Edges: jagged edges sections with flattened peaks Edges: jagged edges sections with flattened peaks Other: surface pitting, small striations, edge crumbling Other: surface pitting, small striations, edge crumbling SEM x

Replica 5: Bone SEM x45 Flake Scarring: irregular, shallow flake scars Flake Scarring: irregular, shallow flake scars Edges: low jagged edges with rounded peaks Edges: low jagged edges with rounded peaks Other: deep striations Other: deep striations3 1 2

Replica 6: Shell SEM x2000 Flake Scarring: regular shallow flake scars Flake Scarring: regular shallow flake scars Edges: jagged peaks with very deep ridges, rounded edges, irregular wear Edges: jagged peaks with very deep ridges, rounded edges, irregular wear Other: crumbling Other: crumbling3 1 2

SEM x100 Flake Scars Comparisons I Replica 4 (Skin) Artifact 1 SEM x45

Comparisons II Artifact 2 Replica 3 (cartilage) SEM x2000 Peaks

Comparisons III Replica 5 (bone) Artifact 3 Striations

Thanks for Playing!

Experimental Variables - Technique - Supplies - Environment

Conclusions I EvidenceConclusion - Wood  pitting - Cartilage  deep crevices - Etc. - Different contact materials create characteristic wear patterns on obsidian - Artifacts lack intentional serration - Replicas did not require retouching - Retouching not required to maintain sharp edge on obsidian blade

Conclusions II EvidenceConclusion - Comparisons of artifacts and replicas - Nonmatches: grass, wood, shell - Closest matches: skin, cartilage, bone - Closest matches to skin, cartilage, and bone - Artifacts most likely used in some type of butchering (range of animal material)

Conclusions III EvidenceConclusion Obsidian blades are… - Rare - Acquired through trade - Not used intensively - Sacred material in other pre-Columbian cultures - Blades not used for everyday butchering  ritualistic function

Final Conclusion RITUAL SACRIFICE Further experimentation required Further experimentation required