Comparative analysis of the glacially deformed Moler Cliffs, Denmark, comprising earliest Eocene, fossiliferous diatomite and volcanic ash layers with contemporaneous deposits. Analysis of geological sites to be compared with the glaciotectonically deformed moler cliffs at Hanklit, Mors, and Knudeklint, Fur, for nomination to the UNESCO World Heritage List

In 2009 the Moler Cliffs were placed on the Danish list of tentative sites for the UNESCO list of World Heritage Sites. In the following years a description of the Moler Cliffs, their scientific importance and unique combination of earth-science elements, was prepared, in order to qualify a submission of the Moler Cliffs under natural criteria viii according to the Operational Guidelines. Two sites, Hanklit (Island of Mors) and Knudeklint (Island of Fur), are appointed as the main representatives of the Moler Cliffs, which aspire to be admitted to UNESCO‟S list of World Heritage Sites. The two sites comprise a serial national property.

„Moler‟ is the local, Danish name for a marine Eocene diatomite, which is exposed in coastal cliffs in the western part of Limfjorden, northern Denmark. The Moler Cliffs expose sections through glaciotectonic complexes comprising pale yellow diatomite (Moler) interbedded with dark grey layers of volcanic ash and overlain by Quaternary sediments. The ash layers record the dramatic volcanic eruptions during the early break–up of the continents bordering the North Atlantic Ocean c. 56 Ma (million years ago).

The diatomite is an exceptional preservation lagerstätte for a range of Eocene fossils, including birds, turtles, insects, fish and plants. The palaeontological importance of the strata in the Moler Cliffs is that they were deposited in an environment, which preserved the fossils very well, hence the term „Fossil Lagerstätte‟. These fossils are significant because they represent faunas and floras documenting the responses to the brief greenhouse event termed the Paleocene–Eocene Thermal Maximum (PETM). The PETM occurred only 10 million years after the mass-extinction at the Cretaceous–Tertiary boundary.

The Moler Cliffs expose sections through glaciotectonic complexes characterized by folds and thrusts. These structures are enhanced by the black layers of volcanic ash interbedded in the pale yellow diatomite. The glaciotectonic deformation elevated the Eocene strata to their present position above sea level and created the hilly landscape, which is so characteristic of the moler area.

The Moler Cliffs are attractive to the public due to their scenic beauty as well as their unique features. The combination of sediments, ash layers, fossils and deformation structures is not known from other outcrops of Early Eocene strata. In addition the Moler Cliffs are of significant interest for scientists investigating the North Sea Basin and the North Atlantic Igneous Province.

The comparative analysis documents the unique features and scientific importance of the Moler Cliffs and concludes that the sites Hanklit and Knudeklint may be admitted to UNESCO‟S World Heritage List under the criteria viii. The combination of three elements referring to criteria viii is considered important: (1) the property records an important geodynamic event, (2) the property includes a palaeontological site, and (3) the property display the unique framework of folds and thrusts created during glacial processes.