Geological Base Map 1:50 000
The Geological Base Map is a series of geological maps providing information about geological background, distribution of mineral resources and groundwater regime in Estonia. This information is essential for a rational use and protection of the geological environment. In Europe and in neighbouring countries, the scale of 1:50 000 is often used for geological mapping. The scale of the Estonian Geological Base Map is also 1:50 000, but there are a few exceptions, where the scale is smaller (e.g. 1:200 000 in the Baltic Sea). From 2003 to 2017, the Land Board (LB) was organizing and financing the Geological Base Map project and distributing the mapping data. Since 2018, the Geological Survey of Estonia has been responsible for mapping, the LB continues to make the data available. Digitized raster maps are accessible through Geological Data Web Map. The Geological Base Map is also delivered as a public WMS service.
Geological Base Map consists of the following series:
- Bedrock map
- Map of Quaternary deposits
- Hydrogeological map
- Map of groundwater vulnerability
- Geomorphological map
- Map of mineral resources
- Map of bedrock relief
- Map of thickness of Quaternary deposits
- Map of aeromagnetic anomalies
- Map of gravity (Bouguer) anomalies
The initial data (geological descriptions of the boreholes, borewells, outcrops and stations) are also included in the Geological Base Map, which is essentially a group of thematic maps (datasets) organized into ESRI geodatabase. The database is downloadable from the Geological Open Data download page.
An overview of the thematic maps
Feature list of the Geological Base Map is given in the mapping guide (Table 3, names dubbed in English).
Bedrock map depicts distribution of bedrock complexes (usually formations) within the outcrop area (on the surface of the ground or under the Quaternary cover). Map is created in accordance with the International Stratigraphic Chart ( 14.48 KB, 26.02.2010 ) that divides rocks into systems ( 643.72 KB, 2.03.2010 ) according to their age. Also information about the distribution of bedrock faults and stratotypes of the regional litostratigraphic units is shown on the map. One or two cross-sections (N-S and/or W-E oriented) accompany every map sheet. An example of the bedrock map ( 248.61 KB, 11.12.2009 )
Map of Quaternary deposits reflects the distribution of sediments in terms of climato-stratigraphic age ( 18.41 KB, 5.03.2010 ) and lithological types. One or two cross-sections (N-S and/or W-E oriented) of Quaternary cover accompany every sheet of the map.
An example of the map of Quaternary deposits ( 315.71 KB, 11.12.2009 )
Hydrogeological map describes the hydraulic conductivity and groundwater storage capacity of bedrocks. It may include information about the conductivity and storage capacity within the Quaternary deposits, if there exists groundwater intake with central consumption and/or the deposits saturated with groundwater lay directly on the crystalline basement. In addition, the map provides information about the groundwater movement directions, quality, mineralization and height of the potentiometric surface. The map also describes the consumption of groundwater by means of distribution of intakes on aquifer systems. One or two cross-sections (N-S and/or W-E oriented) accompany every sheet of the map. An example of the hydrogeological map ( 292.83 KB, 11.12.2009 )
Map of groundwater vulnerability consists mainly of data derived from other geological maps. Natural protection of groundwater within the uppermost aquifer system of bedrock in respect to possibility and speed of potential contamination seeping through the incumbent Quaternary cover is evaluated. Altogether five classes ( 14.56 KB, 5.03.2010 ) are used for assessment. The map of groundwater vulnerability provides information for planning of buildings and constructions, which may affect the environment (e.g. petrol stations, water intakes, etc). An example of the map of groundwater vulnerability ( 244.34 KB, 11.12.2009 )
Geomorphological map is compiled on the basis of data presented in the map of Quaternary deposits and topographical situation. The map provides information about the distribution and formation of landform types. An example of the geomorphological map ( 308.48 KB, 11.12.2009 )
Map of mineral resources reveals discoveries (point features), areas (without reserve calculation) and perspective areas (with calculated reserves, but not included in the environmental register) of the mineral resources. Unlike other thematic maps, no printed map is produced.
An example of the map of mineral resources ( 59.25 KB, 11.12.2009 )
Map of bedrock relief shows absolute heights (in meters above/below the sea-level) of the bedrock by isolines. An example of the map of bedrock relief ( 153.65 KB, 11.12.2009 )
Map of thickness of Quaternary deposits presents the thickness of Quaternary deposits by isopaches. Data is gained by subtracting bedrock relief from topography. An example of the map of thickness of Quaternary deposits ( 135.52 KB, 11.12.2009 )
Map of aeromagnetic anomalies is produced by mapping the intensity of the total vector of the Earth’s magnetic field (T). The measured field data is corrected in respect to secular variations of the Earth’s magnetic field, thereafter the global magnetic field intensity is subtracted. On the basis of the resulting data, statistical surface is generated. Of the statistical surface is compiled an isaritmic map of aeromagnetic anomalies that tend to reflect the variations of magnetic susceptibility of the crystalline rocks in the Estonian basement. An example of the map of aeromagnetic anomalies ( 352.81 KB, 11.12.2009 )
Map of gravity (Bouguer) anomalies is compiled by measuring the acceleration of gravity (g). Based on corrected values, statistical surface is generated of which an isaritmic map is compiled. An example of the map of gravity (Bouguer) anomalies ( 425.1 KB, 11.12.2009 )