Matthew Canti

Calcium Carbonate Features

Publisher Summary The precipitation of calcium carbonate is common in soils and regoliths, especially in soils of arid environments. The precipitation and the accumulation of calcium carbonate in soils and regoliths are very complex phenomena. As they are linked to the interaction between the lithosphere, the biosphere, and the atmosphere, pedogenic carbonates may be important proxies of paleoenvironmental changes. The study of the morphological expression and hierarchical organisation of calcitic pedofeatures in thin sections allows us to partially decipher the climatic, geochemical, and biological influences on the precipitation of carbonates in soils. With the contribution of submicroscopic techniques (e.g., SEM), progress has been made in the understanding of the relation between the biological activity and the precipitation of carbonate, and many calcitic features seem to be linked to biological processes, in a direct or indirect manner. The carbonates may represent a highly active phase, undergoing intense transformation such as recrystallisation, dissolution, and secondary carbonate precipitation.

Morphology and dynamics of calcium carbonate granules produced by different earthworm species.

Granules of calcium carbonate produced by earthworms are regularly found in soil profiles, but little is known of their origins and dynamics. Pure cultures of a range of species were therefore set up, using artificial soils, and the granules recovered for examination. Species of Lumbricus, Aporrectodea, Octolasion and Allolobophora all produced granules larger than 0.125mm, but Eisenia hortensis did not. For comparison, two compost-dwelling Eisenia species were also cultured. These yielded no granules at all, suggesting that the genus as a whole does not produce granules, consistent with its lack of calciferous sacs. Granules recovered from the other 7 species have a variety of sizes and morphologies, ranging from single calcite crystals to aggregations up to 2.5mm in diameter. SEM photographs of the granules and data on granule concentrations in relation to depth are presented

The survey and excavation of a bronze age timber circle at Holme-next-the-sea, Norfolk, 1998-9

In 1998 a circle of timber posts within the intertidal zone on the north Norfolk coast was brought to the attention of the Norfolk County Council Archaeological Service. A subsequent programme of archaeological recording and dating revealed that the structure was constructed in the spring or early summer of 2049 BC, during the Early Bronze Age. Because of the perceived threat of damage and erosion from the sea a rescue excavation was undertaken during the summer months of 1999. The structure was entirely excavated, involving the removal of the timbers and a programme of stratigraphic recording and environmental analysis. A survey was also undertaken within the environs of the site which has identified further timber structures dating from the Bronze Age. Detailed examination of the timber from the circle has produced a wealth of unexpected information which has added greatly to our understanding of Early Bronze Age woodworking, organisation of labour and the layout and construction of timber ritual monuments.

What is Geoarchaeology? Re-Examining the Relationship Between Archaeology and Earth Science

Details of the meaning, derivation and use of the term ‘geoarchaeology’ are discussed with reference to the study scale, the included activities and the level of integration with orthodox archaeology. A distinction is drawn between intensive and extensive archaeology — the two types occupying positions either side of a dividing line at which earth-science analysis moves from a problem-oriented to an integral role, often paralleled by a scale increase to landscape size. The level of integration inherent to extensive geoarchaeology projects means that there are few disparities between expectations and results. With intensive geoarchaeology, however, problems can be caused by the assumption that the techniques used will inform about the environment at a level similar to other specialisms, when in fact they are more commonly involved in context definition and interpretation.