An archaeomagnetic, rock magnetic and magnetic fabric study has been carried out on seven
anthropogenic ash horizons in theMiddle Palaeolithic sedimentary level XXIV at the rock shelter
of Crvena Stijena (‘Red Rock’), Montenegro. The study has multiple goals, including the
identification of iron bearingminerals formed during combustion, assessment of the suitability
of these combustion features for recording the Earth´s magnetic field direction, revelation of
the magnetic fabric and its significance in the characterization of cave (rock shelter) burnt
facies, and identification of post-burning alteration processes. Magnetite has been identified
as themain ferromagnetic component of the ash. The ash layers exhibit a high thermomagnetic
reversibility in contrast to the irreversible behaviour of their subjacent burnt black layers which
is related to the different temperatures attained. Seven mean archaeomagnetic directions were
obtained with acceptable statistical values indicating that these features recorded the field direction
at the time of burning. However, some of them are out of the expected range of secular
variation for mid-latitude regions suggesting post-burning alterations. The magnetic fabric of
the ash was characterized by anisotropy of low field magnetic susceptibility measurements.
Statistical analysis (box and whisker plot) of the basic anisotropy parameters, such as foliation,
lineation, degree of anisotropy and the shape parameter, along with the alignment of the principal
susceptibilities on stereoplots, revealed variation among the ash units. The diverse, oblate
to prolate, lineated or strongly foliated, quasi-horizontally and vertically oriented fabrics of the
units may indicate different slope processes, such as orientation by gravity, solifluction, run-off
water, quasi-vertical migration of groundwater and post-burning/post-depositional alteration
of the fabric by rockfall impact. In sum, the magnetic characterization of the ash layers has
shown the occurrence of different post-burning alteration processes previously not identified
at the site. Alteration processes in prehistoric combustion features are often identified from
macroscopic observations but our study demonstrates that multiple processes can affect them
and are usually unnoted because they take place on a microscopic scale. Their identification
is critical for a correct chronological and cultural interpretation of a site (e.g. collection of
samples for dating, stratigraphic displacement of remains), especially if significant alterations
are involved. Magnetic methods are therefore a powerful but underutilized tool in palaeolithic
research for the identification and evaluation of taphonomic processes affecting prehistoric
fires.
