Are fossils naturally discoverable?

Excursion to prehistoric times: looking for fossils on the Baltic Sea

The stone beaches of the Baltic Sea are an Eldorado for fossil collectors: Especially in winter, countless fossilized relics of prehistoric beings can be found here - unique evidence of a distant past

It may sound a little surprising, but for many people, trips to the beaches of the Baltic Sea are never as attractive as between November and March. Because in the cold months, rain, storms and floods wash rocks from the steep slopes of the coasts. Rubble then collects at the foot of some of the steep banks - and sometimes reveals fascinating treasures: the fossilized remains of primeval creatures that are millions of years old.

They are unique testimonies from bygone geological ages. And you don't have to be a paleontologist or geologist to discover such relics of life in boulders - fossils that give an idea of ​​the diversity of earlier creatures on our planet. If you look carefully through the rubble while strolling, you might discover the remains of old sponges, corals and snails or the crawl tracks of an archaic sea worm preserved in the stone.

It is also quite possible that a so-called rattle stone is lying around in the loose beach gravel, which makes noises when shaken: The curious structure made of flint hides a cavity in which there are loose remains of a primeval pebble sponge. Equally amazing finds are fossilized skeletal elements of the belemnite, an ancestor of our present-day octopus. The Teutons once thought the cone-shaped fragments were sand, which melted into this shape when the god of thunder, Donar, hurled lightning bolts onto the beach. From this legend the name of the fossil has been preserved: "Thunderbolt".

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It is very likely that the surf of a winter storm will swirl amber here and there, the fossil resin of former giant trees, from the sea floor and carry it to the coast. And you hold a rarity in your hands when you discover inclusions in it: a primeval schnake or fungus gnat, perhaps, which got stuck with its legs in the resin of a conifer around 40 million years ago, was drowned by the honey-yellow tree secretion and preserved for all time. Rare pieces can bring in 1000 euros and more.

And so it also explains why strollers on the stone beaches of Rügen, Fehmarn and Heiligenhafen, Bornholm, Fyn or Møn are often stooped - because nowhere else can you find such diverse fossils in such different rocks as in the southwestern Baltic Sea region. The reason for this lies in the checkered geological history of this region. It was mainly formed by several glaciations that began 2.6 million years ago.

At that time the earth cooled down and the Ice Age began. In the high latitudes, especially in the Scandinavian mountains, the snow did not melt as quickly as new fell. Huge layers of ice formed and from then on pushed southwards. The cold periods were interrupted by warmer phases in which the glaciers retreated again.

Northern Germany was last covered by ice around 15,000 years ago; Especially in the east, the glaciers took on enormous proportions: on the land that now forms the Baltic Sea coast of Schleswig-Holstein, several hundred meters of ice weighed down, on the Danish islands and on Rügen a good 1000 meters. And the Scandinavian ice sheet over the Gulf of Bothnia is said to have been up to 3500 meters thick.

In the mountains, the big ice, as glaciers still do today, has ground and rammed rocks, carried away huge amounts of rock debris and dragged it over hundreds of kilometers into the plains, from tiny clay particles to boulders weighing tons. The rubble is still lying in the North German Plain today - an average of 100 meters, sometimes up to 500 meters thick, of sand and clay, pebbles and boulders from the time when climatic conditions like the Arctic prevailed in this country. The material comes to light mainly on the steep banks of the Baltic Sea: There, with little effort, dozens of different types of stones can be picked up, composed of different minerals without any apparent common origin, as well as vast amounts of flint stones.

For fossil hunters, the abundance is a stroke of luck: Because sometimes traces of life from widely spaced periods in the history of the earth come to light here. With a few exceptions, they are all contained in sedimentary rocks, which are formed, for example, by the deposition of clay particles, sand or the shells of dead marine animals. The oldest relics can be found in mostly cream-colored, sometimes also green-gray sandstones from the Cambrian era and are at least half a billion years old!

These are mysterious traces of long-extinct animals that lived on or in the seabed, where they dug tubes close to one another. And with a lot of luck you will see fossilized remains of trilobites - archaic arthropods, the oldest representatives of which lived in the Cambrian and which are related to our modern millipedes, spiders and insects.

Strange organisms

The head and tail shields of agnostids are similarly coveted and sometimes hardly younger; These are little animals a few millimeters long, related to the trilobites, which have been preserved mainly in certain clay and limestone stones. Or the imprints of tiny mussel crabs, 420 million years old, to be found among other things in the "Beyrichien limestone". The remains of early fish can also be discovered in it: spines and bone fragments as well as the tiny teeth of prehistoric sharks.

The snow-white, “only” 70 million year old chalk deposits from Rügen and Møn in turn contain hundreds of different types of interesting fossils - including petrified sea urchins, corals, armpods (brachiopods), fragments of sea lilies and starfish as well as countless sponges (the most common fossils of all). Comparatively young sedimentary stones, on the other hand, are only tens of thousands to two and a half million years old. The fossilized mussels and snails, which can be found quite often in them, are much more reminiscent of today's species.

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Between these extremes, the very old and the younger rocks, on the coasts of the Baltic Sea there is the whole range of all those sometimes strange organisms that once populated the oceans - and which today inspire everyone who tracks them down with a watchful eye as petrified contemporary witnesses. Anyone who deals a little with the appearance and origin of the respective animal and plant relics will be amazed at how multifaceted the world of fossil living beings is - and how quickly an ordinary walk on the winter beach can turn into a surprising excursion into natural history. You just have to look carefully.

Collecting on beaches is allowed in small amounts almost everywhere. In Denmark or Sweden, however, particularly rare finds must be presented to the geological museums. Tips for finding and determining of thunderbolts, sea urchins, fossilized snails and chalk oysters, the book "Collecting fossils on the Baltic coast" by Andrea Rohde offers.