Summary of "7. FROM THE FIELD: Ancient and contemporary stone mining on Rapa Nui"
Scientific Concepts and Discoveries
- Geological Formation of Rapa Nui:
- The island was formed through approximately 12 volcanic events over 700,000 years.
- These events created multiple lava flows of varying thickness and viscosity, forming distinct layers ("cake layer model").
- Key volcanic centers include Tangaroa, Puno Pao, and Vaio Hao in the northern part of the island.
- The volcanic rocks include types such as hawaiianite and olivine basalt, common in the Pacific region.
- Contemporary and Ancient Stone Quarrying:
- The south coast of Rapa Nui hosts both contemporary quarries and ancient mining sites.
- Contemporary quarries supply stone for modern construction (roads, houses, foundations).
- Ancient Rapa Nui people also mined stones in similar locations, demonstrating advanced geological knowledge.
- Archaeological evidence shows at least 21 mining sites nearby, indicating systematic extraction of high-quality stone.
- Types of Stone and Their Uses:
- Kehoe (fine-grained, thin stone): Ideal for making stone tools such as fish hooks, adzes, and knives due to its thin profile.
- Chia (red mineral pigment): Rich in iron and magnesium, used for painting moai statues, body painting (tacona), and coloring artifacts.
- Poro stones (beach-worn boulders): Used as hammer stones for reducing larger stones and as foundation stones in construction.
- Mining and Natural Processes:
- Natural erosion by waves and wind breaks down larger boulders into smaller usable pieces.
- Some caves, like Queho cave, have been expanded over time by both natural processes and human extraction.
- Mining debris (debitage) accumulates around extraction sites, indicating stone tool production activities.
- Archaeological and Geological Methodology:
- Field documentation and mapping of mining sites (21 sites documented for PhD research).
- Use of stratigraphic observation (layers of volcanic flows) to understand island formation.
- Comparative study of ancient and contemporary quarrying techniques and stone use.
Key Points / Methodology
- Examine volcanic layers to understand geological history.
- Identify and classify stone types by texture and composition.
- Document quarry sites and analyze spatial relationships between ancient and modern mining.
- Observe natural erosion and its role in stone availability.
- Study mining debris to infer tool production processes.
- Connect archaeological evidence with geological data to interpret prehistoric resource use.
Researchers / Sources Featured
- Dr. Dale Simpson (PhD researcher and field archaeologist/geologist on Rapa Nui)
Category
Science and Nature
