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164-8 Statistical and Spatial Visualization of Floor Chemistry in Structure 8 at the Ness of Brodgar, Orkney

Session: Advances and Applications of Geochemistry in Archaeology

Presenting Author:

Dorsey Pearson

Authors:

Pearson, Dorsey¹, Pike, Scott², Kitada Smalley, Heather³, Bohn, Haley⁴, Pike, Avery⁵, Card, Nick⁶

(1) Department of Environmental Science, Willamette University, Salem, OR, USA; School of Computer and Information Sciences, Willamette University, Salem, OR, USA, (2) Department of Environmental Science, Willamette University, Salem, OR, USA, (3) School of Computer and Information Sciences, Willamette University, Salem, OR, USA, (4) School of Computer and Information Sciences, Willamette University, Salem, OR, USA, (5) School of Computer and Information Sciences, Willamette University, Salem, OR, USA, (6) Ness of Brodgar Excavations, University of the Highlands and Islands, Orkney, Scotland, United Kingdom,

Abstract:

The Ness of Brodgar, on Mainland Orkney, Scotland, is a large Neolithic complex comprising multiple multi‑phase monumental stone structures dating from ca. 3500–2400 BCE. Excavations indicate that these buildings were neither domestic dwellings nor dedicated solely to food preparation. To investigate how the structures were used over time, a geoarchaeological team is integrating multiple lines of evidence, including X-ray fluorescence spectroscopy (XRF), microstratigraphy, palynology, and archaeomagnetics. This paper reports on advances in statistical analysis and visualization of handheld XRF-derived geochemical data from Structure 8, a multi-hearthed ca. 20 × 9.5 m stone-built monument.

A systematic 50 cm grid sampling strategy was implemented to collect clay floor sediments from across the structure and through different occupational phases. Samples were analyzed at the excavation site with a handheld XRF to assess spatial patterning in major and trace elements. Data was cleaned by removing duplicates, averaging elemental concentrations within grid cells, and filtering unreliable readings. A total of 1381 samples collected between 6 phases were analyzed through the research, allowing for a thorough analysis of the entire structure. Elemental intensities were normalized to the Rhodium (Rh) elastic backscatter signal to correct for instrument variability and matrix effects, then scaled to facilitate comparison. Spatial variation was mapped in R using the elemental data from each square and visualized through an R Shiny application, producing high‑resolution elemental heat maps. The data was faceted by phase to examine the differences of relative concentration between the excavation phases.

This Shiny application was created to act as a tool for archeologists to better examine the geochemical data more efficiently. By organizing the data through the interactive application, examination of all the elements and phases can be done more efficiently when compared to a standard GIS map. This approach highlights subtle geochemical patterning that may reflect activity areas within Structure 8 and demonstrates the value of integrated statistical and spatial visualization techniques for archaeological interpretation.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7905

Statistical and Spatial Visualization of Floor Chemistry in Structure 8 at the Ness of Brodgar, Orkney

Description

Session Format: Oral

Presentation Date: 10/21/2025

Presentation Start Time: 10:10 AM

Presentation Room: HBGCC, 214D

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