Fossil from Denmark (part 2)

Niels Laurids Viby (Denmark)

The first half of the Palaeocene in Northern Europe belongs, more or less, to the Danish! On 16 November 1846, Edouard Desor held a lecture in Paris with the title ‘Sur l’étage Danien, nouvel étage de la crai’ (‘On the Danien, a new stage of the Cretaceous’) – the Danien was, at that time, seen as being the final stage of the Cretaceous period. Nowadays, in most parts of the world, including most of Europe, ‘Danien’ is the recognised name for the geological age stretching from the end of the Cretaceous (somewhere between 64 and 65mya, depending on what book you read) to some five million years later.

Danien deposits are widespread in Denmark, apart from in the southern part of Jutland, and even here you can find flint and blocks of chalk from hardened Danien beds on every stony beach. For fossil collectors from countries that do not have these sediments, Denmark is a good place to visit – it is virtually impossible to come home without at least some Danien fossils, although probably not a great variety unless you visit Fakse Chalk Quarry (which is discussed below).

Danien chalk – a lot of different sediments: Stevns Klint

The layout of the Danien is best seen at Stevns Klint on Zealand, which has some 20km of cliffs, averaging 20m in height.

Here, the bottoms of the cliffs are, in most places, Cretaceous, being from the very top of the Maastrichtian. They are composed of a rather soft sediment that is normally eroded by the sea, leaving the Danien chalk overhanging.

A word on tides: the tidal range is normally less than 60cm in Denmark, so the risk of getting cut off is minimal. However, in stormy weather, with the wind blowing onto the land, it is not very smart to go out; during these conditions there will be no beach to walk on at most coastal sites and certainly not at Stevns Klint. Even if the weather is good, it is definitely best to visit at low tide, as many fossils, such as flint moulds of echinoids, can be found lying on the lower part of the foreshore.

On top of the Maastrichtian sediments is a thin (two to four centimetre) band of ‘Fiskeler’, which literally translates to ‘fish clay’ (unfortunately so-called, not because quality fish fossils can be found in the deposit, but rather for the fragments of fish, such as solitary scales). This is the famous band thought to represent the KT-boundary in Denmark and, at least originally, defined by reason of having an abnormally high content of iridium, seen by some as a proof of the impact of a ‘Dino Killer’ meteorite. 

Unfortunately, for people who like their scientific explanations to be accompanied by loud explosions, several scientists working in different fields have found a number of features of the fish clay that do not fit this simplistic scenario. For example, a new analysis indicates that the iridium is concentrated at the bottom of what is highly permeable chalk, at a point where it cannot disperse downwards any more, as it is stopped by the impermeable fish clay. It might follow from this that the iridium did not originate in the clay, but migrated downwards through the rock column to become concentrated just above the clay. Other analyses indicate that the fish clay was deposed over a rather long period – much longer than the time it would have taken for the airborne debris from an impact to settle.

Even so, it is obvious that the KT-boundary was somewhere around the time when the fish clay was being deposited, as the fossils found below and above it are definitely Cretaceous and Palaeocene respectively. As such, a sample of fish clay is probably one of the best rock examples found anywhere in the world that can be said to represent a mass extinction.

On top of the fish clay is found white, hardened bryozoan chalk that was deposited in easily recognised phases, as bands of flint are common. This rock represents banks at the bottom of a sea that stretched from west of Norway down towards Eastern Europe. (In Fakse Chalk Quarry, which will be described later, the banks are covered with corals). As seen in one of the photos [above], this deposit is much harder than the Maastrichtian sediments that occur below, resulting in overhanging rocks. Cliff falls DO occur, but are rare. However, as a result of these infrequent collapses, there are blocks on the beach that can be searched for fossils.

Here and there, between the white bryozoan chalk and the fish clay, is found a slightly different chalk: the Cerithium Chalk. This deposit is variable, with the lower, white part being very similar the Maastrichtian chalk and the upper, yellowish part being very hard and containing Thallasinoides borrows. This layer is not more than 70cm thick and the fossils found in it are somewhat different to those found in the bryozoan chalk.

Other Danien sites

At some sites in the western part of Denmark, the chalk from the Danien is not as hard as the bryozoan chalk and has, to some extent, the same ‘soft’ texture as the Maastrichtian chalk found elsewhere in Denmark. At some locations, you can find chalk that has a high content of fragments of coccoliths and echinoids, while bryozoans are less common.

The map above shows some locations where Danien strata can be examined. There are other sites, but the ones I have marked are all places where you have free access. Most are coastal cliffs (Stevns, Fornaes and Bulbjerg), while Klim and Karlstrup are abandoned quarries; only Fakse is an active quarry.

There are other abandoned quarries, especially in Jutland, and even a few active quarries. One of these at Dalbyover, north of the city of Randers in Jutland, contains numerous examples of the echinoid, Echinocorys sp. with the shell intact. However, it is important that you get permission by phone from the owner if you want to fossil hunt here – and he does not speak English! If you should be in this area, the best option is to contact the local fossil club and have a member arrange permission for a visit on your behalf.

The quarry at Fakse

A special kind of Danien chalk, the highly fossiliferous coral chalk, is found in a quarry located in the small town of Fakse, south of Copenhagen. This is one of several locations that can be reached using public transport from the city.Hundreds of species of fossils have been found at this site over a period of at least 200 years – but it is still a place where new species can be found.

What is also a pleasant surprise for the amateur fossil collector is that access to the quarry (on foot, no cars allowed) is free. However, you do have to stay away from places where heavy machinery is active. The responsibility, if something should happen, is of course your own, as is made clear on signs in Danish. The path into the quarry is steep and covered with loose and slippery pebbles, and there have been instances of people being hurt and even breaking their legs.

There is a ‘problem’ when collecting in Fakse – the shells of most bivalves and snails have dissolved. What you often find is an internal mould of the specimen but, in many cases, you can take the rock with the counterpart impression of the outer shell and make a cast with liquid rubber – local collectors do this a lot.

There are several different types of chalk at Fakse. The most common is a very hard rock, riddled with holes (not unlike certain types of cheese), where corals have been sitting; this is called ‘pibekalk’ in Danish, referring to pipes. Other fossils, such as sharks’ teeth, can also be found in this material, but are generally not common.

The most fossiliferous rock is ‘coral chalk’ that is largely composed of thin coral branches. You will almost always find small fossils sitting between the corals, for example, carapaces from the crab, Dromiopsis rugosa.

A bit of advice: if you go to Fakse, visit the small fossil museum located in the town. It has an impressive collection of fossils from the quarry and, if it is not sold out, they have a cheap booklet on sale with photos of many of the most common fossils, as well as some rare specimens. While fossil hunting, do not waste time attacking the sides of the quarry; most of the time you will be able to find a pile of waste material to work through. As the coral chalk tends to split along the line of fossils, this is the most efficient way to look at a lot of promising rock faces during your visit.

How to find the sites

This section is split into two parts – one for if you are visiting Zealand and one for if you are visiting northern Jutland. I start first in Zealand, where you can actually reach the three sites mentioned using public transport.

(a) Zealand

Stevns Klint is located south of Copenhagen. If you are travelling by car, head 50km south and then turn east towards St Heddinge, in the town of Køge. From here you have several options, for instance you can access the cliffs at their northern end. To do this, go to the village of Præsteskov, park in the harbour area and walk east along the beach for two kilometres, until the cliffs start. You can also try to find an abandoned quarry called ‘Holtung’, located some eight kilometres down the coast. Unfortunately, this is poorly sign-posted – even Danes can get lost if they are not locals.

Alternatively, the cliffs can be approached from the village of Højerup, where there is access via a step path. Otherwise, you can reach the southern end of the same cliffs from the village of Rødvig. Here, park in a harbour area and follow the beach north for about a kilometre (you can actually see the cliffs from the harbour).

This latter site can be reached by train: you take an ‘S-tog’ (the equivalent of the London Underground), letter ‘E’ to the town of Køge. From Køge station, take a small, local train marked ‘Rødvig’ from the opposite end of the platform to which you arrived. But be careful: only every other one of these trains goes to Rødvig, with the other half going to ‘Fakse Ladeplads’ (this is the train that stops at ‘Fakse Syd’, close to Fakse Chalk Quarry).

To reach Fakse Chalk Quarry by car, travel south on highway E20 towards Gedser and Nykøbing Falster and turn west at turnoff number 37 towards ‘Faxe’ or ‘Fakse’ – the spelling is not homogeneous. When you arrive there, you will need to find the local youth hostel. You can park in the street in front of this and take a path alongside the buildings. When you have passed them, turn left and you will be on the path going down into the quarry. If you want to stay the night, note that youth hostels in Denmark have standards similar to a minor hotel.

Reaching Fakse Quarry by public transport is similar to going to Stevns Klint. Take an S-tog letter ‘E’ to Køge, then a local train to the station ‘Fakse Syd’ and, finally, a shuttle bus that will take you to the centre of the town. The youth hostel is located some 500m to the north-east of the bus terminal.

When actually in the quarry, it is easy to get confused as to where to go – Fakse Chalk Quarry is big. However, the northern end, to which the path leads, is often used by the company that extracts rocks from this quarry as a place where waste material, including coral chalk, is dumped. If you can find a good sized pile, you can easily spend hours finding fossils only a few hundred metres from the path.

There is a third site close to Copenhagen: Karlstrup Chalk Quarry. This is a ‘geosite’ – an abandoned quarry that has been kept as a place where people can study the chalk and search for fossils. It is not very fossiliferous, but echinoids and brachiopods can be found.

The good thing is that this location is very easy to reach: you take the S-tog letter ‘E’ towards Køge and get off at Solrød Strand. Here you take a bus, number 126, going to ‘Høje Taastrup’ – the problem will be making the driver understand that you want to get off next to the quarry. When the bus has crossed a bridge over a highway, it turns right and you have to get off at the next traffic light. The quarry is located on the opposite side of the road, only 300m or so away to the north-east. However, as it is a hole in the ground, you cannot see it before you are standing next to it. I have been to Karlstrup a few times when I was living in Copenhagen – mainly in the winter when desperation for fossil hunting strikes, as Karlstrup is very easy to reach – but I have not found anything of great interest. So, the only reason to go to Karlstrup is if you only have a spare afternoon for yourself, for example, while your family is shopping in Copenhagen.

(b) Jutland

In the north half of Jutland you have several options but these unfortunately have large distances between them.

If you are in the city of Århus, the best option is to go to Fornæs, north of the town of Grenå. This, as with all other sites in Jutland, can only be reached by car. To reach the location, drive north-east to Grenå and then continue north along the coast. After some five kilometres, you will pass a lighthouse and, a bit later, a campsite. Five hundred metres north of this, the road curves sharply to the left, but do not follow it. Instead, take a gravel road on the right and, after 200m, you will be at a beach – your destination.

If you search between the pebbles of the beach, going north or south, you will definitely find flint moulds of echinoids, such as Echinocorys sp.. Some of these have been washed ashore from deposits out to sea. By walking north some 800m, you will come to the southern end of a low cliff made of hardened Danien chalk. At this location, searching in the gravel of the beach and splitting lose blocks of chalk can result in a number of different types of fossils being found, such as small crab carapaces and, with luck, other species of echinoids such as Phymosoma sp., small Salenia sp. and pieces of Cidaris sp.

In the north-west part of Jutland you can visit two locations. North-west of the town of Løgstør is an abandoned chalk quarry, in Klim Bjerge.

To reach this site, travel west from Løgstør, on the north side of Limfjorden to the town of Fjerritslev and follow signs to ‘Klim’. After five kilometres, you will enter a small wood, located on a hill. Here, there is a gravel road to a parking area on the right-hand side of the road, overlooking the quarry. If you do not want to climb down the steep slope at this point, you can walk back to the asphalt road and follow it for some 500m to an overgrown path into the quarry. At first glance, Klim Quarry does not seem to contain many fossils but, with some persistence, it is possible to find interesting specimens. In fact, some found over the last few years have been so rare that they have been declared of scientific interest and, according to the Danish law discussed in my last article in Issue 13 of Deposits, they have been turned over to the National Geological Museum.

West of Klim and north of the island of Mors is the cliff of Bulbjerg. This consists of very hard chalk, where fossils are almost impossible to remove from the matrix without heavy hammers and chisels, and the cliff itself is a protected site. But if you are in the general area for some time, for example looking for fossils in the moler as discussed in my last article, it is a different sort of place to visit (it is the only Danish cliff with seabirds breeding on the nearly vertical face of the cliff).

As discussed at the beginning of this article, there is a small, privately owned quarry north of the city of Randers, some 50km north of the city of Århus. This is one of the most fossiliferous Danien sites in Jutland but, as permission from the owner is required to enter, it is best to contact a local fossil collector to arrange this prior to your visit. The address of the fossil club in Århus is given in the end of the article.

In addition, as discussed above, flint moulds of echinoids and hardened Danien chalk can be found on virtually every rocky beach in Denmark. For that matter, so too can fossils in ice-transported stones from, for example, Sweden. It is actually possible to obtain a large collection of Swedish Silurian fossils from the island of Gotland and Ordovician fossils from Øland without ever visiting either of the places, simply by searching beaches in the southern part of Denmark!

Danish fossils from the Danien

The most common Danien fossils found are flint moulds from the echinoids, Echinocorys sulcata and Echinocorys obliqua. Another echinoid that can be collected is ‘Linthia’ danica. This is found in blocks from the Upper Danien, generally in gravel pits or on beaches. You can also find species of Phymosoma, Temnocidaris and Tylocidaris, as well as the occasional Salenia.

Echinoids with their shell intact are rare, especially in the regular species. However, (generally small) specimens of the regular species can be found in Fakse Chalk Quarry and Echinocorys sulcata, with its shell,  is common in the Dalbyover private quarry mentioned above.

Starfish are nearly always found as lose fragments and sea lilies only as sections of the stem, rarely longer than ten centimetres. Nautiluses are rare. The classic site at which to find these is Fakse Chalk Quarry, but they can be found at other locations.

Bivalves and brachiopods are common, especially in Fakse Chalk Quarry. At this site you can also find snails and crab carapaces from over ten different species. Crab carapaces can also be found at other sites, for example, at Fornæs. However, at the latter site you have to split hard blocks of chalk, so it is easier to look for decapods at Fakse.

However, one special crustacean is not found in Fakse. Palaega danica is a strange animal (I say ‘strange’ as I have not been able to find any literature that locates this crustacean in relation to extant relatives), normally about five centimetres long. This species is most often found in Jutland, in quarries or gravel pits containing hardened chalk blocks.

There are, of course, several types of corals, sponges, bryozoans and worms present in Danien rocks. However, apart from those found at Fakse, it is not easy to determine what you have found. There is no good literature on Danish fossils in general – and certainly not in English. As for vertebrates, the Danien is not the best formation in which to search for these. Undefined fish remains are found now and then and, in Fakse, a few teeth from a type of crocodilian have, on rare occasions, been found.

What can be found are sharks’ teeth. At some sites like Fakse, these are yellow, but at other sites such as Fornæs, they are black. Most specimens are small, between three and eight millimetres but, now and then, bigger specimens are found.

Practicalities

As mentioned above, there is virtually no literature on Danish fossils – apart from a few picture books at a level that makes them suitable for children and not much else! Palle Graversen, an employee at Geologisk Museum in Copenhagen has written the only decent book that can be used by a fossil collector, called Fossiliensammeln in Südskandinavien, published by Goldschneck-Verlag. As it was impossible for him to find a Danish publisher, the potential market in Denmark being too small, he ended up writing the book in German. However, even if you do not speak German, it is possible to decipher the essential meaning using a dictionary for ‘common words’, while geological terms are more or less similar to the English words and are, therefore, understandable.

As far as contacting a fossil club in Denmark is concerned, you do not need to do this if you go to Zealand, as all the locations I mention are open to the public. However, in Jutland you need permission to enter some sites. In these cases you can send a letter to the Fossil Collector Club in Århus and ask for a person to contact. The address is: Jysk Stenklub, Myntevej 16, DK-8240 Risskov, Denmark.

Other articles in this series by Niels Laurids Viby
Fossils from Denmark (part 1)
Fossil from Denmark (part 2)
Fossils from Denmark (Part 3): Getting exercise by walking the beaches of Denmark for fossils
Fossils in Denmark (Part 4): Danish chalk