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Temporal and spatial sources of silica for chert remain poorly constrained. Modern sources to the worlds oceans include silica in rivers > aeolian (dust) deposition > sea floor vents and submarine weathering. However, changes in aridity and dust flux during the Phanerozoic may explain variations in the ocean silica cycle and times and places of chert formation. The chemistry of fine quartz dust (FQD) provides a chemical mechanism for the transformation of FQD to polymorphs of silica in chert; FQD is readily dissolved, then reprecipitated as Opal-A by either biotic or abiotic processes. An unequivocal relation between increases in dust flux and biogenic opal-A in the western Pacific Ocean during the past 200 kyr...
This dataset contains the Digital Elevation Model (DEM) for Africa from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The DEM data were developed and distributed by processing units. There are 19 processing units for Africa. The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. af_dem_3_2.zip contains the DEM data for unit 3-2). The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment...
The Global Human Influence Index Dataset of the Last of the Wild Project, Version 2, 2005 (LWP-2) is a global dataset of 1-kilometer grid cells, created from nine global data layers covering human population pressure (population density), human land use and infrastructure (built-up areas, nighttime lights, land use/land cover), and human access (coastlines, roads, railroads, navigable rivers). The dataset is produced by the Wildlife Conservation Society (WCS) and the Columbia University Center for International Earth Science Information Network (CIESIN). The Human Influence Index (HII) is a measure of direct human influence on terrestrial ecosystems using the best available data sets on human settlement (population...
Le fichier localités de départ est issu de la comparaison de deux bases (PC_Places et GNS). L’identifiant permettant un lien avec les bases origine a été conservé. Les doublons ont été supprimés et seuls deux noms sont proposés (on pouvait avoir a l’origine jusqu’à 6 noms et donc 6 objets différents pour une même localité). Des relevés GPS ainsi que des numérisation sur images satellites ont été réalisés dans différentes portions du territoire afin de compléter le fichier initial. De nouvelles localités sont donc constamment ajoutées à la base. This dataset represents localities from a comparison of two databases (PC_Places and GNS). The identifiers from the original data base are conserved. Repeats were conjugated...
Le fichier a été généré par agrégation des districts. This dataset is made by aggregated the districts into Provinces.
This dataset depicts forest fragmentation in central Africa by roads. This dataset includes roads. This study, or Pilot Analysis of Global Ecosystems (PAGE), examines forest ecosystems of the world using a large collection of spatial and temporal data. This study analyzes datasets at the global, national, and subnational levels, and draws on published and unpublished scientific studies. It develops selected indicators that describe the condition of the world's forests, where condition is defined as the current and future capacity of forests to provide the full range of goods and services that humans need and consume.
Aucune base de données ne disposait du positionnement numérique des ports. Les ports fluviaux correspondent à des noeuds des [axe_hydro]. Ils ont été positionnés par comparaison entre le fichier des localités transmis par la MONUC et, soit la carte des ports transmis par la RVF, soit le listing des ports transmis par la SNCC. En l’absence de ville ou de village portant le nom du port, le noeud a été créé en référence au PK transmis par la SNCC ou la RVF. Le positionnement des ports fluviaux a été fait au sein de l’agence UNJLC de Kinshasa en 2006. No database gives a numerical position of ports. The fluvial ports correspond to nodes on the hydrologic axes. They are positioned by comparisons between the local data...
The data document the results of several microbe bioassays performed by the USGS on Phragmites australis plants, including those performed on mature leaves, seedlings, and dead leaf tissues exploration of the literature to find accounts of microbes associated with Phragmites worldwide. For the bioassays, we prepared 162 pure cultures isolated from Phragmites plants in North America along the east coast, Florida, the Gulf of Mexico, and the Great Lakes area, 125 of which were from a previous study, and 38 represent new collections. The DNA sequences used to identify the 37 new collections are included. Microbes were isolated from plants collected from 2015-2018. We performed assays using both North American plant...
Surficial geology (geo7_2ag).
Categories: Data,
pre-SM502.8;
Types: Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Aaiun-Tarfaya Basin, Province 2066,
Abu Gharadiq Basin, Province 2038,
Africa,
Age,
Amhara Plateau, Province 7161,
This coverage includes arcs, polygons and polygon labels that describe U.S. Geological Survey defined geologic provinces of the Africa. Each province has a set of geologic characteristics distinguishing it from surrounding provinces. These characteristics may include the dominant lithologies, the age of the strata, and the structural style. Some provinces include multiple genetically-related basins. Offshore province boundaries are generally defined by the 2000 meter bathymetric contour, but where appropriate are defined by the 4000 meter bathymetric contour. In some cases province boundaries are delineated by political boundaries, as in the case of The United States and Canada, because United States petroleum resources...
At recent technical conferences, many coal geoscientists in academia and government institutions as well as in industry organizations have expressed concern about the dwindling number of students and young staff members interested in careers in coal geoscience. To better understand what is driving these trends and to identify potential ways that the community can increase interest and participation in coal geoscience, two different surveys were sent to 94 coal geoscientists who were current or past members of The Society of Organic Petrology (TSOP) in February 2020. As the trends and perceptions in industry and government organizations may be different than in universities, one distinct survey was sent to members...
Inland fishes provide important ecosystem services to communities worldwide and are especially vulnerable to the impacts of climate change. Fish respond to climate change in diverse and nuanced ways which creates challenges for practitioners of fish conservation, climate change adaptation, and management. Although climate change is known to affect fish globally, a comprehensive online, public database of how climate change has impacted inland fishes worldwide and adaptation or management practices that may address these impacts does not exist. We conducted an extensive, systematic primary literature review to identify peer-reviewed journal publications describing projected and documented examples of climate change...
Namib Desert. Aerial view of longitudinal dune. Africa. No date.
Categories: Image;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Africa,
Photographers,
aerial,
color transparency (slides)
This article compares US and Chinese incentives in winning oil contracts in African countries. Exploration and development of African oil resources has soared, and many nations are competing for these new oil contracts. China has won a significant portion of these oil contracts due to their unique incentive offerings. This report will address a brief history and the development of Sino–African policies and interests, modern US–African energy policy and interests, petroleum opportunities in Africa, China’s growing oil demand, and information on both American and Chinese incentives strategies. This information will be used to compare US and Chinese incentive strategies on winning African oil contracts. Implications...
This dataset contains the African continent from the Hydrological Derivatives for Modeling and Analysis (HDMA) database. The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment boundaries. The coverage of the data is global (-180º, 180º, -90º, 90º) with the underlying DEM being a hybrid of three datasets: HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales), Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010)...
Boundaries of Uganda's 958 Subcounties as of 2002.
Cette couche SIG rassemble tous les lieux habités de la République centrafricaine; y sont rassemblés tous les villages de tailles importantes, les chefs-lieux de sous-préfecture, les capitales régionales (capitale de préfecture) et la capitale du pays. Cette couche SIG a été obtenue à partir des relevés-terrains (prises de points GPS) par le Bureau Central de Recensement (BCR) de la République centrafricaine, réalisés en 2003. This dataset aggregates all of the inhabited places of the Central African Republic, including villages and important places, courthouses, regional capitals and the capital of the country. These data was obtained from topographic maps with GPS points by the Central Census Office (BCR) of...
This data set contains the Compound Topographic Index (CTI) for Africa from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The CTI data were developed and distributed by processing units. There are 19 processing units for Africa. The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. af_cti_3_2.zip contains the CTI data for unit 3-2). The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment...
This dataset contains the slope for Africa from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The slope data were developed and distributed by processing units. There are 19 processing units for Africa. The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. af_slope_3_2.zip contains the slope data for unit 3-2).The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment boundaries. The coverage...
Ce thème regroupe les limites des permis miniers sur la base des données publiées en mai 2007 par le Ministère de l'Economie, des Finances, du Budget et de la Privatisation. This is a collection of petroleum permits from the public database in May, 2007 from the Ministry of Economy, Finance, Budget and Privatization.
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