Rattle stone
As Klapper stones spherical be flint pebbles designates a cavity in the interior thereof with a freely movable residues of the fossil Kiesel sponge Plinthosella squamosa located. Most balls have a diameter of about four to seven centimeters, although some specimens can be significantly larger.
Emergence
The diatomite of the silica sponge skeleton in the upper chalk ( writing chalk ) formed the basis for the creation of the flint balls, which can be found in existing writing chalk, for example on the Baltic islands of Rügen and Møn , and in the Quaternary debris . During its lifetime, the sponge had numerous root-like growths, between which the finest lime sludge (chalk) settled after its death. Over time, spherical flint accumulated around him. The flint bowl usually has openings that are easily visible to the naked eye, which originate from the outgrowths of the pebble sponge, for example its short handle. These openings later provided the seawater with an ideal point of attack to penetrate the interior of the flint ball and first to rinse out the chalk residues there. Over time, the skeletal parts of the pebble sponge connected to the inner edge of the flint ball also dissolved. What remains is a spherical fossil sponge, now loosely in the flint ball, which can move freely in the interior. If such a stone was added and shaken, the clatter of the back and forth moving sponge residue is heard - hence the name Klapperstein . Most of the balls do not rattle, however, because either the sponge residue has not yet detached from the flint coating or has already completely dissolved under the influence of the penetrating seawater.
Rattling stones in the true sense of the word, i.e. flint balls in which the fossil remains of the pebble sponge move freely, cannot be found in the writing chalk itself due to the formation conditions described above. However, they occur everywhere in the bed load of northern Germany and Denmark in outcrops (e.g. gravel pits) and on beaches, but are not common.
use
The flint balls were once local, e.g. B. on the French Channel coast, used as grinding stones. Larger spherical shotguns are said to have also been used as cannonballs on the Danish island of Møn.
See also
literature
- Kurt Hucke : Introduction to bed load research . - 132 p., 50 plates, numerous Text illus., Nederlandse Geologische Vereniging, Oldenzaal, 1967.
- Andrea Rohde: Looking for fossils on the Baltic Sea . - 272 p., Numerous Fig., Wachholtz-Verlag, Neumünster, 2008.
- Werner Schulz: Geological guide for the north German bed load collector . - 507 p., Numerous Fig., Cw Verlagsgruppe, Schwerin, 2003.