University of Southampton OCS (beta), CAA 2012

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Detecting the causal action, mapping the spatial distribution consequence: Geostatistic approach in chemical residues at intra-site level.
Alfredo Maximiano Castillejo

Last modified: 2011-12-22

Abstract


The main objective in archaeological spatial analysis is quantifying the variance in terms of spatial pattern. The classical issue proposes plausible interpretation of distribution in key of cluster structure and insolates remains, which are related with the most probably causal action that generated them.

 Usually, the locations of distribution remains are associated like the places where people had made something. Under this thinking, archaeologist establish a peculiar relation in terms of nominal category of remains and the use of space (e.g. the distribution of debris is the place where people worked with lithic instruments,… but what would happen if these people manage their residues and re-deposit remains in other places? Then, we are detecting an activity related to waste management and not the production of lithic utensils). The last trivial example could become a real situation in our archaeological records, because we cannot perceive actors making actions, we only can perceive a fraction of theirs materials consequences. Then, although we have applied sophisticated data capturing process and statistics tolls, the inherent complexity of the archaeological records make us fall into a set of incongruence interpretations about the spatial variability detected.

We would re-thinking our epistemological point of way in terms of consider different background in which anaction could take place in determinate set of locations, and under determinate spatial structure. Them, may be define under its material consequences (e.g. chemical residues distribution) the probably place where the action was made and therefore, we can establish a congruence discussion about probably use of space. Based on the foregoing considerations, this proposal is interesting in investigate the relation between geostatistical approach, analytical visualization (GIS) and a particular archaeological data: Chemical residues like consequence of determinate human activities.

Geoestatistic approach is an option recently incorporated in archaeological spatial analysis at intra-site level. This approach working with continuous spatial data, like chemical residues (different variable intensity in every localization). In others words, geostatistics resolve the question: how a property varies depending its position in terms of spatial structure and (auto)correlation measurement. This is very interesting when we are looking forstructural limits, influence areas, activities places… Questions we cannot perceive according to a classical analysis of distribution vestiges.

The chemical residues (phosphate, fat acid…) are  a data type where this premise (spatial continuity) is true, and in term of archaeological spatial thinking, if we apply geostatistic tools in this data type, we can quantification the spatial structure (auto-correlation in terms of spatial semivariance), predictive and simulation models of distribution in areas where prospection is so complex or not possible (kriging), and last, mapping the more probably location of causal action in terms of spatial attraction or repulsion (spatial gradient).

Therefore, we consider an excellent opportunity connecting chemical residues, geostatistic approach and GIS visualization in key of:

i.     A new exploration methodology and interpretation way for archaeological site; and secondly,

ii.     It can be derived actions distribution maps in terms of theirs materials consequences.

 


Keywords


Geostatistic; GIS visualization; Chemical residues, intra-site