Abstract
Here we present the first assessment of microfocus X-ray tomography
(micro-XCT) as an analytical technique to generate data about
macro-fractures on small quartz backed tools similar to those currently
held to represent the oldest known evidence for bow hunting.
Our experimental results are derived from 21 replicated quartz
backed tools randomly selected from a population (n=218) that were
broken in a controlled hunting context. We used 3D data obtained
from micro-XCT scans to identify macro-fractures and to derive more
accurate measurements for these fractures. Our results demonstrate
that the micro-XCT technique overcomes reflected-light challenges
associated with analysing quartz through conventional macro-fracture
approache s. We were able to increase the total observed macrofracture
sample by 33% compared with conventional approaches
using a hand-lens. Whereas macro-fracture data could be refined, the
additionally gained data did not change interpretations obtained from
a conventional macro-fracture analysis. It did, however, marginally
change the degree of significance in differences between the different
applications. During this study, we also detected micro-fracture
features, such as possible fracture wings and microscopic linear impact
traces (MILTs).With further studies, the morphometric traits of these
micro-fracture features could be useful for distinguishing between
ancient weapon-delivery systems.