The Læså Formation is a
lower Cambrian
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovici ...
unit exposed on the Baltic island
Bornholm
Bornholm () is a List of islands of Denmark, Danish island in the Baltic Sea, to the east of the rest of Denmark, south of Sweden, northeast of Germany and north of Poland.
Strategically located, Bornholm has been fought over for centuries. I ...
, comprising two members: the lower, the Broens Odde Member, colloquially and previously informally termed "green shales" (Grønne Skifre), a 100 m thick
glauconitic
Glauconite is an iron potassium phyllosilicate (mica group) mineral of characteristic green color which is very friable and has very low weathering resistance.
It crystallizes with a monoclinic geometry. Its name is derived from the Greek () m ...
silt-
sandstone
Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
occasionally bearing extremely
acritarch
Acritarchs () are organic microfossils, known from the Precambrian to the present. The classification is a catch all term used to refer to any organic microfossils that cannot be assigned to other groups. Their diversity reflects major ecolog ...
-rich
phosphatic
Phosphates are the naturally occurring form of the element phosphorus.
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphor ...
pebbles; gradually transitioning upwards into the upper, the 3 m thick Rispebjerg Member, a sandstone.
[Clausen C.K., Vilhjálmsson M. 1986. Substrate control of lower Cambrian trace fossils from Bornholm, Denmark. Palaeogeogr. …Palaeoclimatology, Palaeoecol. 56:51–68.]
References
Geologic formations of Denmark
Cambrian System of Europe
Paleozoic Denmark
Paleontology in Denmark
Formations
{{europe-geologic-formation-stub