Day 1. Departure from Lund University at 9:00 am.
Mid to Late Jurassic sandstones and coal seams exposed
in Eriksdal, Southern Sweden. Plant fossils have been identified from these sediments. Photo: Vivi Vajda
|Stop 1. Eriksdal, Mid- to Late Jurassic sandstones and coal seams.
Eriksdal is situated 20 km north of Ystad in the Vomb basin. The Jurassic strata are exposed in the quarry run by Fyleverken. The strata is vertically tilted, slightly overthrusted. The oldest sediments include the Earliest Jurassic (Liassic) ferruginous sandstones followed by the so called Eriksdals beds of Bajonian age, Glass sand of Bathonian age (stratigraphic chart). This is followed by the green, plastic Fyledalen Clay of Kimmeridgian-Portlandian age. Plant fossils have been encountered in these sediments.
In the afternoon we drive to Ystad, from where we take the ferry to Rønne, "capital" of Bornholm. This ferry trip takes around 1h 30 min and the sea is normally nice and calm during this time of the year.
Stop 2. Arnager Town. Upper Cretaceous Cenomanian Arnager Greensand Fm and Coniacian Arnager Limestone Fm.
Near the town of Arnager on the south coast of Bornholm, the Upper Cretaceous deposits are exposed in a small cliff. The Arnager Greensand consists of fine-grained glauconitic quartz sand which is strongly bioturbated. The overlying Arnager Limestone is an uniform marl, silica-rich grey and white chalk deposited on a system of complex mounds on the sea floor. The lowermost layer is a 20 cm thick conglomerate composed of composite glauconized and phosphatized pebbles of chalk, and greensand.
Lower Cretaceous deposits exposed along the coast
of the Danish island, Bornholm. The sediments are
composed by cross-bedded and massive quarts sand
with a vast number of trace fossils. The underlying sediments yield plant fossils and ostracods.
Photo: Vivi Vajda
|Stop 3 and 4. Jydegård, Robbedale and Rabekke Formations at Arnager Bay.
The Lower Cretaceous deposits on Bornholm belong to the Nyker Group of Berriasian to Valanginian age. The Nyker Group comprises three formations; the Rabekke, Robbedale and Jydegård Formations. We will make the first stop at Arnager Bay where the three formations are exposed in a coastal setting.
The age of the lower Jydegård Formation is Late Berriasian- Valanginian corresponding to the German 'Wealden' and is equivalent to the Upper Purbeck, as well as to the lower Ashdown Fm., which is the base of the Hasting Beds of the type Wealden in Britain. The quarts sands and clays of the Jydegård Formation interfingers with the underlying Robbedale Fm.
The Robbedale Formation is composed by cross-bedded and massive quarts sand with a vast number of trace fossils (e.g Sholithos) of which some are interpreted as feeding traces of rays. The sediments belonging to the formation were deposited in a shallow marine environment. The entire formation is of Berriasian age and is correlated with the lower part of the German 'Wealden'.
The sediments of the underlying Rabekke Formation are composed of fluviatile and lacustrine to marginal marine green and black clays and sand of an supposedly Berriasian age. The deposits yield plant fossils and ostracods.
Arrival and check in at Hotel Skovly
Day 2 (August 16th)
We depart from Hotel Skovly at 8.30 to spend the day at the coastal sections at the western and southern shore of Bornholm. This will be a long day walking at the beach sections. Lots of drinking water recommended. Bring sunhat, long sleeves, swim wear etc.
Early Jurassic plant fossils from the Bagå Formation. These terrestrial sediments are exposed at the south-western
coast of the island of Bornholm. Photo: Vivi Vajda
|Stop 5-6. Hasle Clay pit/ Korsodde|
The principal exposures of the Bagå Formation occur at the Hasle brick-factory clay pit and in the coastal cliff section in the vicinity of Korsodde. The Formation reaches a thickness of c. 400 m and encompasses the late Pliensbachian to Bathonian. Today most of these sediments are inundated but sediments at the edge of the clay pit and in blocks around it. The Bagå beds are also exposed along the coast south of the Clay pit.
The Bagå beds consist of interbedded sand, clay, and coal beds with rootlets below and the dominant facies is a laminated, grey to dark grey clay with occasional silt and sand lamina. Plant fragments including small logs, stems and leaves are common in the clay. Plant macrofossils are common in the formation and were described in the late 1800. The depositional environment of these sediments was those of paralic, lacustrine and alluvial settings. No marine macrofossils have been encountered but dinoflagellates have been indentified from the basal beds.
Stop 7. Galgeløkken
Sinemurian sandstones intercalated with clay layers are exposed at this coastal locality stretching for 400 m along the beach. The sediments are part of the so called Galgeløkken Member and makes up the upper part of the Rønne Formation. The layers, which comprise a total thickness of up to 210 meters, are slightly dipping and becoming older towards the south.
|The lithology consists of thin sand and clay beds interpreted to have been deposited in a tidal, delta environment. This locality is known by its interesting sedimentary structures.
Barbeque at Hotel Skovly
Jurassic (Sinemurian) sandstones intercalated with
clay layers are exposed along the south coast of
Bornholm. The sediments are stretching for 400m
along the beach and are interpreted to have been
deposited in a tidal delta environment. The locality
is known for its interesting sedimentary structures.
Photo: Vivi Vajda
Day 3 (August 17th)
Hammershus Castle ruin. This fortress is located at Bornholms´ north-western point, and defended the island at various times from the mid-13th Century through the 1600s. Photo: Vivi Vajda
|Stop 8. Hammershus Castle ruin. |
We leave our hotel at 8.30, driving north to Hammershus Castle ruin, a historically interesting site. We continue our tour around the island stopping at historical villages and scenic spots. On our way back along the south coast time will be given to visit a few more geological/archaeological sites, depending on time. The sun will be up until 10 pm so there is plenty of time for fieldworks.....
Stop 9. Risebæk, Late Triassic (Carnian)
The Risebæk member, which is part of the Kågeröd Formation, reaches a thickness of 70 metres, exposed along the southern coast of the island. The exposed sediments consist of multicolored (red-greenish) plastic clays of a Late Triassic, Carnian age. Within the clays, white, calcrete nodules are encountered formed as caliche in the Late Triassic arid climate. These clays were formed on a coastal plain with meandering rivers depositing channel-sand.
Triassic deposits are un-conformably overlain by the Early Jurassic Rønne Fm.
Risebæk, Late Triassic. The Risebæk member, reaches a thickness of 70 metres,
exposed along the southern coast of the island of Bornholm. The exposed sediments
consist of multicoloured, plastic clays of a Late Triassic age. These clays were
formed on a coastal plain with meandering rivers deposition channel-sand.
Photo: Vivi Vajda
Day 4. (August 18th).
Check out from Hotel Skovly
Visit to Rønne Geological Museum. End of fieldtrip, participants can either take ferry to Copenhagen, Sweden or Poland.
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Sivhed U. 1980: Lower Jurassic ostracods and stratigraphy of western Skåne, southern Sweden. Sveriges Geologiske Undersökelse Serie Ca 50, 84 pgs.
Sivhed U., 1984 Litho- and biostratigraphy of the Upper Triassic-Middle Jurassic in Scania, Southern Sweden. Sveriges Geologiske Undersökelse Serie C 806, 3 1 pgs.
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