Trampling Impact

This paper presents the results of a trampling experiment on obsidian artifacts conducted as part of a larger archaeological program aimed at assessing the effects of postdepositional processes on lithic artifacts. Flaked artifacts were made from obsidian nodules from Huenul source (Neuquén, Argentina) and were laid on two plots-hard and soft substrate. Here we report the breakage frequency and artifact metric variables relevant for fracture occurrence. Following the methodological proposal to assess the Trampling Fragmentation Potential (TFP), we apply the data mining technique known as decision tree to analyze the experimental obsidian datasets. Results show that fracture ratio is significantly higher on hard substrates, and that the value of maximum fracture thickness shows no variations in obsidian. Finally, including the obsidian dataset to the decision tree showed that certain raw materials may modify the relevant variables and/or their influence on the TFP.

RESUMEN
Como continuación de un proyecto destinado a contribuir al conocimiento arqueológico de los efectos de los procesos post-depositacionales sobre los materiales líticos, se realizó una experiencia de pisoteo sobre artefactos de obsidiana. El experimento incluyó el planteo de dos pistas-una sobre sustrato blando y otra sobre sustrato duro-en las que se depositaron artefactos experimentales manufacturados a partir de nódulos de obsidiana procedente de la fuente Huenul (Neuquén, Argentina). Siguiendo la propuesta planteada para evaluar el Potencial para la Fragmentación por Pisoteo (PFP), los datos experimentales son analizados con la técnica de data mining denominada árbol de decisión. Se informan las frecuencias de fractura y las variables métricas artefactuales relevantes en su ocurrencia. Como fuera registrado en experimentaciones previas, se observó que el sustrato duro promueve la ocurrencia de fracturas y contrastamos los espesores máximos de fracturas obtenidos. La incorporación de los datos de obsidiana al árbol de decisión mostró que ciertas materias primas pueden modificar las variables de relevancia y/o su influencia sobre el PFP.

Palabras clave: experimentación; obsidiana; potencial para la fragmentación por pisoteo; tafonomía lítica.

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