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In this work, the presence of obsidian in the lower Amazon of northern Ecuador is discussed, from a geoarchaeological perspective, emphasizing the dynamism of the river landscape. The information from archaeological excavations at the Payamino site, the lithic analysis of the tools, X-ray Fluorescence characterizations of obsidian, analysis of stratigraphic profiles, the use of geographic information systems and palynological data were taken as reference. All this information points to the fact that the obsidian from alluvial fans of the Coca, Napo and Payamino rivers was transported by floods and violent expulsions of deposits accumulated in the northern sub-Andean mountain range of Ecuador, specifically from the Quijos river. In this way it is evident that obsidian in lower Amazon of Ecuador, was not exchange between from the Andes to the Amazonia. [ABSTRACT FROM AUTHOR]

Due to the lack of subsoil geological information of the alluvial sediments, has been created a urban geology database for the Caracas Valley. These geological data base supports a geological proposal of 11 microzones considered homogeneous for seismic microzoning, which have been reflected on a quaternary map of geological formations and faults. The characterization of each microzone is based on the geological evaluation of 7 parameters considered as significant. [ABSTRACT FROM AUTHOR]

The objective of this research was to identify the areas of high mineral potential within the region with gravel and sand deposits associated to the fluvial system. The investigation was conducted in the southern plain of Pinar del Río, excluding the southern-western portion. Various types of evidence maps representing the criteria produced by the descriptive models for this type of ore body were used in the forecast as well as data of the geological processes that originate them. Boolean logic models and indexed overlay were used in order to integrate the maps in GIS (Geografic System Information) platform. The weight of the attributes was estimated based on the available geological data about ore bodies of this kind. The integration methodology used indicated that the plain had high potential of having deposits of sand to be used for construction purposes, revealing 24 potential sectors; the majority is no farther than 15 kms from the main towns and cities. A detailed study on the fluvial system allowed dividing the plain into 6 areas with sub-homogenous drainage patterns and different favorability levels. The most potential sector within the plain is an elongated and narrow strip of land to the NE-SW; which takes up the central portion of the plain, below the pre-mountain. Lastly, the gamma-ray spectrometry (potassium channel) is proven to be useful in regional studies for identifying potential alluvial ore bodies of sand and gravel. [ABSTRACT FROM AUTHOR]