GEOLOGICAL INFORMATION about chalk from Lägerdorf
Schleswig Holstein is a young land which was formed by the period and the post-glacial periods. Together with a large part of Northern Germany and almost the whole of Denmark it would have been sea bed, if the periods of Cenozoic had not considerably increased its structure. However, the subsoil consists of solid rocks which connect the mountainous regions of Central Germany and the rock caves of Scandinavia.
In many million years the chalk deposits became enormous layers. Often it took an entire millennium to form 1 - 2 cm of sediment. Supposing that 2 cm per millennium is the medium sedimentation velocity, 400 m write chalk - this layer package results from the different profile sections for the open minings in Lägerdorf and Kronsmoor - deposited in approximately 20 million years. This period was also established by advanced physical determinations of the age.
Furthermore sea urchins are often present. In most cases they are filled with chalk, however, often they are silicified. The forms are different: heart-shaped, ball-shaped and small, halved ellipsoid. Sea urchins of the same kind show different developmental stages. The orifices of the body are distributed both symmetrically and asymmetrically. There are only fragments of shells and sea urchins. Furthermore skeletons of dinosaurs of the Jurassic period are said to be found in Lägerdorf. There were silicious sponges and other life-forms with silicious skeletons in the chalk sea, too. You still find traces of silicious skeletons of the sponges, however, the silicate framework is now replaced by brown iron ore. The silicious mass of the sponges and of other life-forms disolved in long periods of time and was then separated as jelly and enriched again.
In Lägerdorf there is a flatly strained vault which was brought up from the depth by means of the elevation of the salt dome to the earth's surface during the middle Tertiary; it is streaked with fragments, polished by inland ice, and covered by a thin morainic layer. The thickness of the chalk profile determined until now with certainty amounts to 250 m. Boring in the pit resulted in chalk being determined at 200 m. Furthermore, already a 4 % brine was detected which proves the existence of the salt dome under the chalk. In Lägerdorf the spoil layer above the chalk is 3 - 10 m. The minable area comes to app. 10 km².
The deposits of the Cenozoic clearly differ from those of chalk. They predominantly consist of marls, clays, pebbles, and sands, and apart from some deposits of the Paleogene, they are soft and loose. The Holstein Gestein originated in the Neogene and can also be found in Itzehoe. This is a sand stone which is rich in shells; many boulders of it can be found in our clay and sand pits. This is sand strengthened by ironcarbonate which contains a variety of different and well preserved sea shells and snails. Deposits of mica clay from earlier lap formations also belong to this formation.
That the geest island of Münsterdorf is an original island was made evident to us during the big storm tide in 1962, when the Stördeich (the Stör dike) broke and the surges dashed against the old beach line at the edge of the village Münsterdorf. Today the Nordoer Dünen still show the former sandy beach. Due to a slow but clear lowering of the whole land the North Sea could gradually reach the geest borders. At the end of the last glacial period it still was approximately 20 - 60 cm higher than today. The change between land and sea in our homeland took place very slowly during long periods of time.
(Source: Lägerdorfer Chronik II)
Cenocoic Alluvium (present time and post-glacial period)
|since 20,000 years||exisiting|
|Diluvium (glacial period)||1 million years||exisiting|
|Tertiäry||60 million years||exisiting|
|Middle ages||upper chalk||50 million years||to be found near Lägerdorf|
|lower chalk||30 million years||to be found near Lägerdorf|
|Jurassic||35 million years||exisiting|
|Trias (variegated sandstone)||40 million years||Helgoland|
|Antiquity||Perm||40 million years||to be found near Elmshorn and Segeberg, together with chalk it forms the mountain subsoil|