Moclay basin

Theme: The Moclay basin 

Locality: Hanklit.
Description of a Danish GeoSite

Primary identification

Primary geological features

7. Main topic:
Moclay.

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, and due to exceptional mineralogy.

13. Comparable GeoSites:
In Denmark: The seacliffs of Silstrup, Northern Mors, Fur and Erteb�lle Hoved (GS 3-2, 3-3, 3-4, and 3-5) are supplementary GeoSites.

Supplementary data in support of the locality 

14. Delineation on a map:
 

15. Higth of the GeoSite:
Exposures are up to ca. 61 m high.

16. Area of the GeoSite:
Not applicable.

17. Subordinate geological interests:
Geomorpology, Fossil and mineral hunting.

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

19. References:
B�ggild, O.B., 1918: Den vulkanske aske i moleret samt en oversigt over Danmarks �ldre Terti�rbjergarter. Damn. Geol. Unders., II. rk., 33.
Gry, H., 1940: De istektoniske forhold i moleromr�det. Med bem�rkninger 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 L�gst�r. kvart�re aflejringer. Danm. Geol. Unders., I. rk., 26.
Gry, H., 1964: Furs geologi. Dansk natur - Dansk skole. �rsskrift 1964.
Jensen, K.E.S.K. & Pedersen, S.A.S., 1989: Geoelektrisk opm�ling 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 afl�gger efter 29 mill. �r. 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 p� Mors. Mors - kort og godt, 1. Mors� 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.

20. Data sources, collections:
...

21. Illustrations:
Photo:

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

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

24. Recommandation:
Hanklit is the main GeoSite within the Moclay basin.

25. Comments:
....

26. Supplementary description:
....