Skip to McMaster Navigation Skip to Site Navigation Skip to main content

Geoarchaeology

Unearthing the Past: Geoarchaeology at Stélida

Geoarchaeology integrates techniques from the Earth Sciences to tackle archaeological challenges. At Stélida, we employ these methods to decode ancient human-environment interactions, revealing how this site may have played a crucial role in facilitating hominin migrations across the Aegean Basin during the Pleistocene.

A form of chert close to chalcedony, occasionally veined, often fractured, and ranging in colour.

The Distinctive Chert of Stélida

Séfériadès (1983) first characterized the Stélida chert as a variant closely resembling chalcedony – occasionally veined, frequently fractured, and displaying a diverse color spectrum from white to blue to pink.

Despite its striking appearance, it has generally been regarded as relatively low in quality.

Geological Insights from the Cyclades

A vital aspect of SNAP’s research is the geoarchaeological survey, led by Prof. Nikos Skarpelis, with assistance from Dan Contreras. Prof. Skarpelis brings extensive geological expertise on the Cyclades and has previously conducted a mineralogical study of Stélida. This research was carried out under a permit from the Institute of Geological and Mining Exploration.

Mineralogical Investigation of Stélida

This study aimed to:

  • Map and characterize the chert outcrops, assessing the accessibility of raw materials alongside their color, macro- and micro-texture, banding patterns, and overall knapping quality.
  • Examine intra-source chert variability, particularly in relation to its use as a lithic raw material, by integrating geological observations with artefact distribution data.
  • Collect a representative set of geo-referenced geological samples for petrographic and elemental analysis, conducted at Prof. Skarpelis’ laboratory in Athens.
  • Utilize characterization data to trace the distribution of Stélida chert across Naxos and the southern Aegean, reconstructing procurement and exchange networks centered around the source.

We focus here on Prof. Skarpelis’ key preliminary observations.

At Stélida, the striking rock formation is characterized by thick tabular beds, showcasing its unique geological structure.

Petrographically, it is classified as a brittle, massive sedimentary rock with pervasive silicification, highlighting the intricate processes that shaped it over time.

It is extremely hard, exhibiting conchoidal fracturing and a semivitreous, vitreous, or waxy luster.

Its coloration ranges from very light grey to white, with some areas displaying a subtle honey-toned light grey.

Secondly, the highest-quality chert is found at the southern peak of Stélida, where it outcrops along both the eastern and western flanks.

Thirdly, as one moves northward along the ridge, the rock becomes increasingly sandy and less suitable for flaking, with a few exceptions. This shift in material properties may largely account for the noticeable decline in artefact density along those transects.

Fourthly, good-quality raw material is also exposed at the base of a modern quarry on the northeastern flank of the headland; however, due to its depth, this chert was likely inaccessible to prehistoric populations.

Advancing Research: Next Steps in Geoarchaeological Analysis

This study is set to yield further insights, particularly following the completion of petrographic analyses – utilizing both a petrographic microscope and a Scanning Electron Microscope (SEM) – as well as elemental characterization of geological samples through Inductively Coupled Plasma-Mass Spectrometry (ICP-MS).

In 2014, our focus included examining the patination of artefacts across the site to determine whether variations in surface weathering on stone tools serve as indicators of age or reflect localized processes of exposure and erosion.