Drejø

Drejø is located 15 km southwest of Svendborg in the central part of the South Fyn Archipelago. Public access to the island is by the ferry ‘M/F Højestene’, which departs several times a day from Svendborg throughout the year. Drejø covers an area of 4.3 km2 and has a coastline measuring
16.3 km in length. Of all the smaller islands in the South Fyn Archipelago, Drejø is the only one to have its own church, which was built in 1535. It has a somewhat unusual location - not on a prominent hill, but in a natural hollow outside Drejø village - all because of a local legend.

Geology

Most of the glacial landscape is a gently undulating moraine plain, with the low hills on the south-eastern part of the island showing a slight southeast-northwest-trending orientation. A small erosional valley orientated northeast-southwest intersects the landscape just west of Drejø By (‘Drejø Town’).
Data obtained from up to 34 m deep water exploration wells (GEUS. dk) indicate that the subsurface of the island comprise layers of predominantly till(s) intercalated with meltwater sands and-gravels and several meters thick bodies of olive grey meltwater clay and -silt. At 21 selected well-sites, no
indications of marine Eemian deposits have been reported; however, it is possible that some of the layers interpreted as glacial meltwater clay could, in fact, be Eemian sediments, e.g., the stone free ‘Shiny Clay’ which is lacking macro fossils. Marine Eemian deposits are present in the coastal cliffs at Næbbesodde.

Næbbesodde, the westernmost part of Skoven, features a 1-km-long and up to 12-m-high active coastal cliff mainly consisting of till sediments. However, observations made before 1908 show that floes of yellow sand, blue-grey stone-free clay, alternating clay and sand layers, Eemian ‘Shiny Clay’ and ‘Cyprina Clay’ are present in the Quaternary succession as well. This was confirmed during fieldwork in 2019. The ‘Cyprina Clay’ contains
abundant shells, often concentrated in shell-horizons. The few outcrops of the ‘Shiny Clay’ revealed décollement surfaces, which is a common feature of this unit. No thorough investigation of the glacial deposits has yet been carried out at this site. Preliminary studies conducted in 2019 seem to indicate the presence of several till units.

Coastal landscape

Following the Holocene inundation, ‘Drejø’ comprised two separate moraine islands: Skoven (‘The Forest’) to the west (highest point 17 m) and Drejø to the east (highest point 9 m), which were subsequently amalgamated by the tombolo/beach ridge system called Drejet (hence, the name ‘Drejø’). A third remnant of the glacial landscape is present just east of Skoven. Drejø exhibits a variety of young coastal landforms governed by topography and postglacial hydrodynamic conditions. Like many of the other islands within the Archipelago, the southern coast is partly erosional and simplificated, whereas the northern coast is more protected and is characterized by shallow waters and ongoing sedimentation.

To the northeast, Høllehoved is a barred (and embanked) marine foreland with beach meadows. In 1995 a nature restoration project was launched and as a result, the lake Nørresø was formed. Today this area boasts of a rich birdlife. The northern end of Høllehoved, called Knappen, consists
of glaciofluvial deposits. Today it is an embanked grassland connected to the main island by a small tombolo. At the tip of Knappen a small recurved spit has recently formed. Further along the northern coast towards the west, the two coves Vigen and Madekrog are separated by Langesodde, a protruding part of marine deposits that superimposes the low-lying glacial sediments.

It should be emphasized that the available data and literature contain some contradicting opinions regarding the extension of the glacial landscape on Høllehoved and Langesodde. Erosional products from the Næbbesodde cliffs have formed a major marine barred foreland complex, Digerne and Mejlhoved, with several beach ridges, beach meadows, and beach lakes. It is currently prograding further towards the east, terminating in the spit Mejlhoved Odde and it has entirely incorporated the western half of the tombolo, Drejet. In general, traditional dikes embank many of the marine forelands on the island, causing interference with the natural land-forming processes and hampering interpretation of the development history of these areas.

The southernmost part of Skoven is a low-lying meadow, Tørvegravene (‘The Peat Pits’), which, according to the literature, partly consists of  freshwater deposits from the ice age’, but no further data have been found to support this assumption. Some postglacial marine deposits are also present in the outer parts of this area. This is similar to the meadow areas around Søndersø (‘the Southern Lake’) at the southeastern point of Drejø. 

Most beaches on Drejø are narrow and stony with some sandy patches on the less exposed stretches. Many large stones and boulders are present near or onshore around the island. Some are erosional remnants from the glacial landscape, but quite a few have been deliberately placed to provide coastal protection. One km north-northeast of Knappen lies the tiny islet of Grydholm, which is merely a 75-m-long, narrow, stony and sandy reef with some large boulders (residual of eroded glacial deposits) at the northern end. The existence, shape and size of this islet is entirely governed by hydrodynamic factors and local weather conditions. Thus, it is a representative of several similar islets, sand- and gravel bars throughout the   archipelago. On topographic maps from 1842 to 1940 Grydholm was 130 m long, 50 m wide and up to 1.3 m high but has since decreased  considerably in size. Another interesting aspect is that Paleolithic artefacts have been found on and around Grydholm.

Exploitation of Geological Resources

Near the tip of Næbbesodde, a crescent-shaped plateau halfway up the cliff represents a former clay pit once belonging to Drejø Brickworks, which was operative from around 1900 to 1917. The former owner of a nearby farm bought a demolished brickwork from Tiselholt Manor near Vejstrup Ådal  ‘Vejstrup stream valley’ and shipped the materials to Drejø. All houses on the island built within this period are made of Drejø bricks. Moreover, most of
the production was exported. Due to financial problems, the brickworks closed in 1917 and was sold to Stenstrup Brickworks, who demolished it soon  afterwards to avoid competition. Old brick waste and wall debris can still be seen on the beaches below the cliff. Postglacial peat has been dug in minor pits at Tørvegravene.

Value

The geology of the coastal cliff and the cultural history of Drejø Brickworks adds to the interest of this island as does the great variety of Holocene coastal landforms and their importance as grazing areas and bird habitats. Drejø is protected under the EU Natura 2000 area no. 127 and Habitat area H111. The site is also classified as part of GS 5-2, part of NGI 128 and part of NCA 42 and an EU Bird Directive protected area (BD71). The northeastern and eastern coast of Drejø borders the The South Fyn Archipelago Wildlife Reserve, which is designated in accordance with the Ramsar Convention. The Ramsar area (no. 156) is part of the EU Natura 2000 network.