kreidefossilien.de • The Saxonian-Bohemian Cretaceous

Update 11/29/2020: The „Geologische Übersichtskarte GÜK400“ of Saxony available at the ArcGIS Feature Service is the „Oberflächenkarte“ version (surface map), where Cenozoic sediments (Paleogene-Recent) are shown. Thus, I used this version of the GÜK400 (without Cenozoic sediments). Read more about the three different versions of the GÜK400 of Saxony (in German).

There does exist compiled maps of the SCB-BCB which extends over the Czech Republic, Saxony and Poland. For example in Greguš et al. 2013 there is a picture of Cretaceous Basins in Europe - containing the BSCB, the North-Sudetic Basin, Intra-Sudetic Basin/Nysa Through. One disadvantage of using such a pre-compiled image of a map occur when doing modifcations like adding own labels or other own data. Hence, I created a map of a similar style within QGIS. It's georeferenced and pretty detailed about the actual extends of (known) occurences of Cretaceous sediments. It is not a paleogeographic map, but a map showing exisiting Cretaceous sediments more or less near the surface. This map is based on data of the Geological Surveys of Saxony, Czech Republic and Poland. All three geological surveys offer a so-called ArcGIS REST Service. These can be accessed within QGIS quite easily. Because the finished map had to be re-used in a GIS, I searched for data available in vector formats, not Raster-Images. Considering the overview approach of such a map, geological data of larger scales seemed to be sufficient. I used geological data provided in a scale between 1:400.000 and 1:500.000 (GK400 and GK500). The following REST-Services were added in QGIS as „ArcGIS-Feature-Service“ and used:

https://geoportal.umwelt.sachsen.de/arcgis/rest/services

with the layer /geologie/geologie/MapServer/1 (GÜK400 - 1:400.000) by the LfULG Sachsen

http://mapy.geology.cz/arcgis/rest/services/

with the layer /Geologie/geologicka_mapa500_en/MapServer/6 (GK500 - 1:500.000) by the Česká geologická služba (CGS)

https://cbdgmapa.pgi.gov.pl/arcgis/rest/services/

with the layer /kartografia/mgp500k/MapServer/0 (GK500 - 1:500.000) by the Państwowy Instytut Geologiczny/Państwowa służba geologiczna (PGI/PSG)

This three URLs needs to be added as an ArcGIS-Feature-Service within QGIS. In contrary to a Web-Feature-Service (WFS) the perfomance of the REST-Service is much better. Using them within the webbrowser might not work (at the moment the service by the PGI is disabled for webbrowsers).

Due to different national standards concering the CRS/SRS (projections/spatial reference systems) I decided to convert the data into the WGS84 projection (EPSG:3857) which is commonly used e.g. within the Google Maps and OpenStreetMap projects. The de facto "standard" for Saxony is EPSG:25833 (ETRS89 UTM 33N), for Czech Republic it seems to be EPSG:102067 (5514) and for the polish data it is EPSG:2180 (ETRS89). The reprojection of the data was done with QGIS if necessary. A missing WKT/proj4-definition needed for the reprojection can bee obtained by the linked datasets with the proper EPSG-codes. When added and used as a custom CRS (Settings→Custom Projections) a reprojection with a sufficient level of accuracy can be done.

Subsequently adding the geological maps in a vector format, the datasets then had to be adjusted by modifying the areas which should be joined together. Beacuse of the different databases a custom modification had to be done at the joined areas (See images below). The "holes" within some enclosed areas indicate e.g. the occurence of iintrusive (e.g. paleogene/neogene in the eger-graben) remnants. This areas were not modified.

After adjusting all the data, the three data-layers were processed with the "Vector-Dissolve", "Vector-Merge" and "Shape-Repair" Tools from the QGIS-Toolkit and exported into a geopackage (*.gpkg), *.geojson and a *.png file (plus *.pgw world-file).

The QGIS project, showing the compiled map (BSCB = green) on top of the three used geological maps (colors brightend) provided by the german, czech and polish geological surveys.

The Bohemian Cretaceous Basin („České křídové pánve“) and the Saxonian Cretaceous Basin („Elbtal-Gruppe “ = s.l. „sächsische Kreide“) within the country-borders of Germany, Czech Republic and Poland (1:200.000). The small area just near the border between North-Bohemia and the very southeast of Saxony - the „Zittauer Sandsteingebirge“ - is genetically part of the BCB.

Download the data/map showing the BSCB in BRD-CZ-PL (WGS84 - EPSG:3857):

• GEOJSON (use for GIS)
• KML (use for GIS)
• GEOPACKAGE (sth. like shape-files - use for GIS)
• PNG (400dpi) - can be used within a GIS with this world-file: PGW
• SVG

Update: For Poland a version of the 1:1.000.000 map without cenozoic sediments can be found in the layer /kartografia/mgpbk1000k/3. The image below shows the 1:1M map without cenozoic, filtered for „Cretaceous“ (green colors) polygons.

Update 12/17/2020: Now, a more extensive version with all the Cretaceous Basins/remnants around the Bohemian Massif is available, too.

Compiled map of Cretaceous Basins around the Bohemian Massif

• Raster-PNG: cretaceous-basins-bohemian-massif.png with Worldfile cretaceous-basins-bohemian-massif.pgw
• Vector-PDF: cretaceous-basins-bohemian-massif.pdf

Map-Data, based on the following sources:

• Digitale Geologische Karte von Thüringen 1 : 25.000 - Thüringer Landesamt für Umwelt, Bergbau und Naturschutz (TLUBN)
  Data licence Germany – attribution – version 2.0 govdata.de/dl-de/by-2-0
• Geologische Karte von Bayern 1:500.000 - Bayerisches Landesamt für Umwelt (LfU), www.lfu.bayern.de
  Creative Commons Attribution 4.0 International (CC BY 4.0)
• Geological map without Cenozoic deposits 1:1 000 00 - Polish Geological Institute/National Research Institute (PGI/PSG)
  http://geoportal.pgi.gov.pl and https://gis.pgi.gov.pl/en/
• GÜK400 Kanäozoikum abgedeckt von Sachsen& Digitale Geologische Karte von Sachsen (GK50 dig) - Sächsisches Landesamt für Umwelt, Landwirtschaft und Geologie (LfULG)
  Data licence Germany – attribution – version 2.0 govdata.de/dl-de/by-2-0
• Geologische Übersichtskarte der Bundesrepublik Deutschland 1: 250 000 (GÜK250), Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Hannover, 2019
• Geologická mapa České republiky 1 : 500 000 - Czech Geological Survey (ČGS)
  Creative Commons BY 4.0 license (Attribution International)
• Beer, H. 2010. Oberkreide - Verbreitung und Mächtigkeit. Karte 17. In: Stackebrandt et al. Atlas zur Geologie von Brandenburg, 4. Auflage. Landesamt für Bergbau, Geologie und Rohstoffe Brandenburg (LBGR).
• Borders, Cities and Rivers by eurostat, European Commission - ec.europa.eu/eurostat/