Research on hardened daub fragments provides highly relevant data on the building activities of past societies. Unfortunately, in many cases these elements are not considered relevant research objects, resulting in a very important loss of information for archaeology. There is still a long way to go in the studies of earth building remains, the vast majority of which have focused on assemblages coming from specific sites. Likewise, a good number of these studies carried out from a macroscopic approach either have not published the methodology used or barely offer some considerations about it. This article approaches the methodological procedures for their analysis through direct observation, while hoping to contribute to making these remains more visible and to facilitate and promote their study. This methodological proposal can be applicable to materials of different composition and from very different contexts, chronologies, and origins.

Being sessile filter feeders, sponges may be disadvantaged by sediments in many ways, e.g. through clogging and burial. However, in order to correctly recognize negative effects of sediments in the field, natural relationships of sponge taxa adapted to a life with sediments need to be understood. The present publication reviews available literature and provides observations on natural and beneficial interactions of sponges with sediments, distinguishing several strategies: (1) Saving energy through sediment incorporation, reducing or replacing spicule production commonly occurs in keratose, verongimorph, tethyid and poecilosclerid sponges, which often received scientific names referring to sediments. (2) Forming sediment crusts externally or embedded in surface tissues reinforces outer layers, provides shade, and for external crusts camouflage and shelter from spongivory and desiccation. External crusts often occur in the tethyids and axinellids, while surface armour is most common in keratose sponges. (3) Anchoring in soft sediments provides a selective advantage for space colonization. This is mainly achieved in the hexactinellid, polymastiid and spirophorine sponges by using spicules (predominantly in deeper water), commonly in endopsammic sponges by rootlets, basal agglutination and basal incorporation of particles, and in various groups by attachment to buried materials (shallow water). (4) Living at least partially embedded in sediments (psammobiosis) appears to be best developed in Oceanapia spp. and bioeroding sponges, generates shelter from various external conditions and reduces the risk of spongivory. Typical morphological characters of sediment-adapted sponges are thus sediment skeletons and surface crusts (reinforcement), stalks and fistules (elevation above sediments), spicule tufts and root-systems (anchoring).

A new corer is described which may be used in sediments of shallow standing waters, such as in rice fields, and which facilitatesthe study of the vertical distribution of the invertebrate fauna at 2 cm depth intervals. Its small surface area permits quantitativesampling of the sediment-dwelling fauna, particularly the chironomid larvae, around the roots of rice-plants. Results arepresented and the efficiency of the sampling method is discussed.

L'étude de la solubilisation du manganèse dans les eaux des forages du champ captant de Capdenac-Gare (complexerivière-nappe) met en évidence deux processus différents de réduction du métal :— l'un, permanent, est lié à la présence de matière organique particulaire enfouie dans les sédiments récents ou déposéesur le fond du Lot, dans les zones de calme ou de retour (effet de vase). L'implantation de forages pompant l'eauau travers de ces zones mène inéluctablement à des concentrations élevées en manganèse et au traitement de l'eau prélevée ;— l'autre, saisonnier, est lié à la présence de matière organique dissoute dans l'eau du Lot, essentiellement fourniepar le développement algal en été (eutrophisation).La minéralisation de cette matière organique au niveau de la berge (effet de berge) entraîne la consommation de l'oxygènedissous puis des nitrates accompagnée d'une baisse du potentiel redox. Il s'ensuit une mobilisation du manganèseau niveau des biofilms du milieu poreux, mobilisation favorisée par les températures élevées de l'eau du Lot, en été eten automne.Lorsque le carbone organique bio-dégradable est épuisé on observe une réoxygénation de la nappe par la surface,accompagnée de la précipitation du manganèse soluble. Il faut donc éviter l'implantation de forages dans la zone réduiteet favoriser, lorsque c'est possible, la réoxygénation de la nappe par la surface.

This study attempts to ascertain whether the differing provenance sources and plate tectonic settings of deposition of clastic sediments and rocks can be identified by chemical means, thus opening the increased use of these rocks and their metamorphosed derivatives in plate tectonic modelling. Mineralogically immature feldspathic and mafic sands, muds, sandstones and shales from Mesozoic, Cenozoic and Holocene clastic deposits in California, Oregon, Alaska and Colorado have been both modally and chemically analysed providing a valuable data base (217 samples; 216 samples chemically analysed, many for 28 elements).

There is significant upward chemical variation in the Great Valley sequence of California which mimics previously described petrographic variation and in turn reflects provenance changes with igneous episodes and erosional stripping of the Sierra Nevada in late Mesozoic time. Differing sandstone petrofacies result in varying chemical signatures and while the provenances of monomict sediments are easiest to identify, polymict sources involving granitoid or ophiolitic material can often be identified by potassium feldspar or Cr contents. The distinction of K which is derived from detrital potassium feldspar from K derived from detrital illite, micas or other sheet minerals, is best made by a Niggli al–alk plot against k. Mafic sandstones derived from mafic volcanic or plutonic rocks preserve essentially mafic igneous chemistry and could be possible parent sources of some amphibolites which grade into metasediments. The lithified erosion products of the Sierra Nevada calc-alkaline igneous rocks have higher Niggli al–alk and higher average Niggli si at any given mg value than the fresh igneous rocks enabling meta-arkoses to be distinguished from meta-igneous rocks.

Applying previously published chemical criteria gives the actual plate tectonic setting of deposition of most of the sandstones studied. This suggests that the chemical composition of sandstones can yield much more information about the provenance and plate tectonic setting than hitherto recognised.