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Theme 3: Supplementary GeoSites to the Moclay basin

The Moclay basin 

Localities: Silstrup, Northern Mors and Ertebølle Hoved.
Collective description of supplementary Danish GeoSites to Theme 2

Primary identification

1. GeoSite no.:
GS - 3-3, 3-4, and 3-5.

2. National locality no.:
NGI - 18-21 and 24.

3. GeoSite name:
Moclay localities.

4. Location:
Denmark; Northern Jutland.

5. Co-ordinates UTM:
System ED50, Zone 32: 
x=479348, y=6309090;
x=484600, y=6299194; x=495049, y=6308813;
x=500522, y=6298918.

6. Type of locality:
Moclay quarries, coastal cliffs, and landscapes.

Primary geological features

7. Main topic:

8. Geo(morpho)logy:
Moclay is a marine diatomite with low clay content, which was deposited in a restricted area in the Western Limfjord region. The moclay is interbedded with volcanic ash and calcareous concretions.
Thick beds of moclay are bioturbated contrary to thin beds, testifying differences in status of oxygenation of the Paleocene-Eocene sea bed.
The more than 170 ash layers are related to the vulcanism in the Norwegian Channel in Skagerak associated to the opening of the Atlantic Ocean and constitute an exceptional tool for stratigraphic correlation.
The moclay contains well preserved vertebrates (fish in particular, but also birds, turtles, and others), as well as many insects.
All exposures of moclay are capped by glacial till and have suffered glacial deformation (folding and thrusting), which is reflacted in the geomorphology. Localy there is Upper Oligocene micaceous clay overlying the moclay and testifying a hiatus from Early Eocene until then.

9. Frame / context:
Sedimentology, Petrology, Paleontology, Diagenesis.

10. Chronostratigraphy:
Paleocene-Eocene and Weichselian.

11. Primary value:
Glacially dislocated and deformed moclay, which shapes the landscape.

12. Comparative evaluation:
Stratigraphy: Stolle Klint, Knude Klint and Silstrup Klint er type profiles.
The moclay succession is of international scientific importance as it is a rare lithotype, due to its importance in correlation, because of preserved fosils, due to exceptional mineralogy.

13. Comparable GeoSites:
In Denmark: In addition to Silstrup, Northern Mors and Ertebølle Hoved there are the main GeoSites Hanklit (GS 3-1) and Fur (Stolleklint and Knudeklint).

Supplementary data in support of the locality 

14. Delineation on a map:

15. Higth of the GeoSite:
Exposures are up to ca. 60 m high.

16. Area of the GeoSite:
Not applicable.

17. Subordinate geological interests:
Geomorpology, Fossil hunting.

18. "Non"-geo interests:
Raw materials, Tourism.

19. References:
Bøggild, O.B., 1918: Den vulkanske aske i moleret samt en oversigt over Danmarks ældre Tertiærbjergarter. Damn. Geol. Unders., II. rk., 33.
Gry, H., 1940: De istektoniske forhold i molerområdet. Med bemærkninger om vore dislocerede klinters dannelse og om den negative askeserie . Meddr. dansk geol. Foren., 9.
Gry, H., 1979: Beskrivelse til geologisk kort over Danmark. Kortbladet Løgstør. kvartære aflejringer. Danm. Geol. Unders., I. rk., 26.
Gry, H., 1964: Furs geologi. Dansk natur - Dansk skole. Årsskrift 1964.
Jensen, K.E.S.K. & Pedersen, S.A.S., 1989: Geoelektrisk opmåling af Hanklit. Danm. Geol. Unders. Intern rapp., 58.
Petersen, G.K. & Surlyk, F., 1983: The Fur formation, a Late Paleocene ash-bearing diatomite from northern Denmark. Bull. geol. Soc. Denmark, 32.
Heilmann-Clausen, C., 1994: Sydklinten ved Silstrup - hvordan en diatomit fik en aflægger efter 29 mill. år. Varv, 1994, 4.
Pedersen, G.K. & Buchardt, B., 1996: The calcareous concretions (cementsten) in the Fur Formation (Paleogene, Denmark): Isotopic evidence of early diagenetic growth. Bull. geol. Soc. Denm., 43.
Pedersen, S.S., Pedersen, G.K. & Noe, P., 1994: Moleret på Mors. Mors - kort og godt, 1. Morsø Lokalhistoriske Forlag (also available in Engelish and German).
Pedersen, S.A.S. & Petersen, K.S., 1988: Sandfilled frost wedges in glaciotectonically deformed mo-clay on the island of Fur, denmark. In: Croot, D.G. (ed.): Glaciotectonics. Forms and processes. Balkema. Rotterdam.
Schmitz, B., Peucker-Ehrenbrink, B., Heilmann-Clausen, C., Åberg, G., Asaro, F. and Lee, C-T. A., 2004: Basaltic explosive volcanism, but no comet impact, at the Paleocene-Eocene boundary: high-resolution chemical and isotopic records from Egypt, Spain and Denmark. Earth and Planetary Science Letters 225, 1-17.  

20. Data sources, collections: 
The Moler Museum ( ) and the museum of Fur ( ). 

21. Illustrations:

22. Proposers:
Dansk Geologisk Forening & Det Kongelige Danske Geografiske Selskab

23. Description by:
Based on Andersen, S. & Sjørring, S. (eds), 1997: Geologisk Set, Det Nordlige Jylland. Skov- og naturstyrelsen & Geografforlaget, 208 pp.

24. Recommandation:
Silstrup Hoved,  Northern Mors and Ertebølle Hoved are supplementary GeoSites to the GeoSites Hanklit (GS 3-1) and Fur (Stoleklint and Knudeklint) within the same theme.


26. Supplementary description:

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Anholt og ØsterrevBoerupBovbjerg KlintFroeslev PlantageGram LergravHanklitKalksøjler ved HirsholmeneKarlby klintKongens Mose Lille VildmoseLønstrupSkagens OddeStensbaek PlantageUrhøje og Myrhøje PlantagerVadehavetFur (Stolleklint and Knudeklint)

Theme: Moclay basin
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Last modified : Friday 29. Dec., 2006 Erik Nygaard
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