Appropriate technology for low cost geological mapping Guyana Guyana has a mineral base economy and the Geological survey is keen to adopt low cost mapping and data gathering techniques to improve efficiency. Guyana is dominated by tropical rainforest and is obscured by cloud for most of the year making it difficult to gain Landsat imagery that is of any use. Radarsat however can effectively image tropical regions and has the benefit of high spatial resolution making it the most appropriate imagery for this region. It was decided to run a pilot study in the Bartica area of north central Guyana which is low lying and has three main rivers running through it that would provide route ways through the dense rainforest. Fine beam Radarsat imagery was purchased via the internet and a Landsat 5 Thematic Mapper image was procured through collaborative work with the National Resources Management Project. On screen Geological interpretation was carried out prior to fieldwork and then hard copy and digital maps were taken into the field for ground truthing. Whereas dense rainforest and patchy cloud obscured all geological information on the Landsat 5 image, the Radarsat image clearly showed the structural and limited lithological information which allowed a preliminary structural map to be compiled prior to fieldwork. This map could then be used to pin point areas of interest within the study area. 
Fig. 4:Landsat 5 Thematic Mapper false colour image of the Olgi District, Baruun Altai, Western Mongolia showing clear colour coded differences in Geological entities. Mongolia The range of climate zones within Mongolia means that Landsat 5 and Landsat 7 are the most appropriate types of remotely sensed data for studying this country. Online internet searches helped to locate cloud free Landsat data for regions within the geological mapping and mineral exploration programme of Mongolia Mineral Resources Authority (MRAM). Four project sites were chosen and the data for these areas were processed as band composites, principle components and band ratios. The output was then displayed on 1:50,000 and 1:200,000 scale plots for geological interpretation in the field. Enhanced imagery such as band ratios is particularly effective in discriminating certain clay and oxide rich lithologies in the arid Gobi desert of Southern Mongolia. Decorrolation Stretches (principle components) however helped to map out major geological units and fault structures in the Baruun Altai of Western Mongolia (Figure 4). GPS was also used to locate field sites in order to geocorrect the raw image data to the local map projection system. Conclusions Feedback from the Geological surveys involved in the case studies suggests that data gathering rates have been substantially improved by the use of remotely sensed data and GPS as part of a structured programme of interpretation and fieldwork. The true development in this project lay in the report generating aspect and we believe that we are producing a web site that will prove invaluable to Geological surveys and other Government mineral institutes worldwide. We feel that this site will help Geological Survey Organisations and individuals to realise the full potential of cost effective sustainable technologies such as Remote sensing, GIS and GPS. Acknowledgments This paper is published with the permission of the Director of the British Geological Survey.
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