... the maggot stones from Freital ...
The Doehlen basin at the outskirts of Dresden, named after one of the villages making up the town of Freital, is one of the geologically most thoroughly investigated regions of Germany, owing to the former coal and uranium mining.
It is a trough repeatedly sunk in and filled up during the Upper Carboniferous and Lower Permian, accumulating up to 600m of Rotliegend sediments. Four major sedimentation cycles can be distinguished, with mineable coal seams in the second one. The plant fossils found in the barren strata (mostly compressions, partly in 3-D preservation) were of practical relevance as index fossils. Less attention had been paid to the fossiliferous cherts from the latest sedimentation cycle (Bannewitz formation), which nearly always are found as displaced fragments only. From a paleaobotanical point of view, the chert is of much interest even as loose pebbles and boulders since it can bear much more structure information then the often conspicuous carbonaceous impressions. A small remainder of fluvial deposits, probably from the Cretaceous, is the type locality of the Permian foliage Scolecopteris, the "maggot fern", whose stems are well known as Psaronius. Parts of the fronds, stems, and extended root systems in the silicified mud and peat are among the most common fossils in these cherts.
The favourable conditions for chert collecting due to groundwork in the area of the chert-bearing deposit are approaching its end now.
