Soil micromorphology
Reconstructing the complex formation histories of stratified archaeological sequences is better achieved through the analyses of undisturbed sediments using the technique of soil micromorphology. Micromorphology allows for studying intact (i.e., undisturbed) sediment samples. Studying intact, contextualized samples is key because, as we dig, we break apart the original relationship between the sediments and the artefacts they embed, erasing depositional geometries and structures that provide knowledge on the formation histories of a deposit.
There is a growing awareness that sediments are not only the “dirt” that needs to be dug out of a site, but that they are fundamental parts of the archaeological record, on par with other types of more traditional archaeological artefacts. Archaeological soil micromorphology is at the forefront of this research and this technique has been used to evaluate the dynamics of deposition and post-depositional (i.e., after burial) processes forming the archaeological record. Furthermore, thin depositional events might be invisible during excavation, though they are readily identified under a microscope.
To achieve this, micromorphological samples are carefully carved out of archaeological deposits as blocks and consolidated (using a resin-based impregnation) to maintain their original context. From the consolidated sediment blocks, micromorphological thin sections (a 30 µm-thin veneer of the original deposits) are produced, which can be examined under the microscope at several magnifications. The remaining consolidated sediment blocks are, in effect, left over mirror images, of the thin sections manufactured for observations under a microscope.