Egebjerg Bakker og Stenstrup Issø

Egebjerg Bakker and Stenstrup Issø (Egebjerg Hills and Stenstrup Ice Lake) is a magnificent glacial landscape located 8-10 km northwest of Svendborg. East of the Svendborg motorway, the area is bordered by Højes Dong Hills with the viewpoint Højbjerg at 112 meters.

There are parking lots at Egebjerg Mill and the Danish Nature Agency's area at Bakkelundgård. In Egebjerg Bakker there are marked hiking trails, including a stretch of the Øhavsstien. Around the area there are picnic areas, a packed lunch house, a shelter site and several good viewpoints.

In Egebjerg Mølle, a former windmill from 1861, you will find the Egebjerg Mølle Naturrum information center with exhibitions about the area's natural and cultural history. It is open around the clock, all year round. The nature room is designed to inspire visitors to go out and experience nature on their own. For schools and institutions, there is equipment for playing and learning in nature. From the unique glass prism at the top of the mill, you get a great overview of the ice age landscape and the South Funen Archipelago.

Near Egebjerg Mølle is the protected Rødme Svinehaver (Pig-gardens of Rødme, Funen's finest grassland. The area has never been cultivated, but has been grazed for centuries. This has created a species-rich vegetation with many rare plant species.

North of Egebjerg Bakker, at the end of the last ice age, Weichsel, was Denmark's second largest glacial lake - Stenstrup Ice Lake. The clay layers in the lake have been exploited since the Middle Ages. In addition to a number of small brickworks run by local farms and smallholders, from the mid-18th century until 1987, there were 13 larger brickworks around Stenstrup and Kirkeby. Now only Pedersminde Teglværk remains. The bottom of the former meltwater lake is now fertile farmland.

If you want to experience the area in its full extent, you will have to use a bicycle or car.

The ice age landscape in Egebjerg Bakker and Stenstrup Issø

Egebjerg Bakker is a 5.5 km long, 3 km wide and up to 110 m high marginal moraine pushed up from a southerly direction by the part of the Bælthav Ice Stream (18-17,000 years before present) known as the 'Little Belt Glacier'. The hills consist of interbedded layers of moraine and meltwater deposits along with layers from the Eemian interglacial (130-115,000 years ago), the Weichselian 'White Sand', and interspersed with 60 million-year-old clay layers from the Paleocene period.

The east-west ridges are clearly visible in the landscape and can be experienced as a roller coaster when driving along Skovmarksvej and Alpevej between Egebjerg and Ollerup. Between some of the ridges are small lakes and bogs where peat was once collected for fuel.

In Rødme Pig Gardens, you can see a so-called stone sprinkling. These are large stones in the soil surface that still lie where the ice once left them.

To the east, the north-south running marginal moraine Højes Dong Bakker was created by the part of the Bælthav Ice Stream known as the 'Great Belt Glacier'. When the glacier stopped and became dead ice, part of the marginal moraine was covered by a dead ice landscape in the form of large dome-shaped hills, including the 112 m high viewpoint Højbjerg.

In the lowlands around Stenstrup, large amounts of meltwater were dammed up, creating Stenstrup Ice Lake. To the south, the meltwater lake was bounded by Egebjerg Bakker, to the west and north by dead ice from two previous ice advances and to the east by the Great Belt Glacier and the hills at Højes Dong. The main inlet to the lake was in the southeastern corner at Sellebjerg, where a large lake delta of sand and gravel was built up. The finer clay was carried out into the deeper parts of the lake further northwest and deposited as thick layers of meltwater clay. The water depth in the ice lake varied between 10 m and 25 m.

As the dead ice to the west melted, the lake spread over a larger area, gradually lowering the water level. Traces of the former lake shores can now be seen as low 'cliffs' that lie at different heights in the adjacent landscape. Eventually, the meltwater lake was emptied of water through Hørup Å and Hundstrup Å.

What remained were some small water-filled depressions on the former lake bed. These deposited various lake deposits reflecting the climate fluctuations at the end of the last ice age - from arctic cold to a short-lived mitigation called the Allerød period (13,900-12,600 years before present), where animals and a low scrub forest temporarily re-emigrated before the ice age ended with a final cold period, the Younger Dryas (12,600-11,700 years before present). During our current warm period, the Holocene, peat was formed in the depressions. Thus, the layers in Stenstrup Ice Lake contain nature's own archive of many thousands of years of climate development.

Utilization of Geological Resources

This part of the Geopark is rich in geological resources and there have therefore been numerous clay, sand and gravel pits in the area. Today, the resources are only exploited in two locations: the clay pits at Præstevænget, which supply clay to Pedersminde Brickworks in Stenstrup, and the large gravel pit at Sellebjerg operated by the construction company NCC.

In 2012, the estimated clay resource in Stenstrup Issø was around 1 million m3 of red clay and 11.5 million m3 of blue clay. The total thickness of the various clay deposits in the ice lake is around 6 m. It should be added that there is a general lack of suitable deposits of red clay in Denmark.

Clay from Stenstrup Ice Lake has been exploited since the Middle Ages. Together with an unknown number of very small brickworks run by local farms and smallholders, there have been around 13 large brickworks in the area around Stenstrup and Kirkeby from the mid-18th century until 1987. This industry was of great importance to the local community in terms of economy, infrastructure, employment, etc. Today, only the fully modernized Pedersminde Brickworks is in operation.

Traces of the industrial heritage are still present in the area, although all the former brickworks (except Pedersminde) have been demolished or converted into modern buildings that house various small industries. Most of the former clay pits have been completely restored or filled with water and now serve as biotopes for birds and amphibians, for example.

The landscape in the future

The site has a large area and is composed of many different landscape elements such as marginal moraines, dead ice landscapes, moraine surfaces and the former lake bed from Stenstrup Ice Lake. Each individual landscape element is characterized by special terrain and soil conditions that make the area complex in relation to future changes.

From a geological perspective, the glacial landscape itself is unlikely to change in the foreseeable future. The greatest immediate threats are considered to be, for example, the inclusion of new areas for raw material exploitation and the development of large areas for solar cell installations, wind turbines and forest planting, etc.

In terms of raw material exploitation, this takes place in specially designated areas - in particular around Sellebjerg in the southeast corner of the Stenstrup Ice Lake system, where the ice lake delta's large sand and gravel deposits have been exploited for over 100 years. Furthermore, Pedersminde Teglværk periodically excavates clay (primarily blue clay) in the area around Præstevænget in small clay pits a few meters deep. In both places, the excavation of raw materials constantly creates illustrative profiles in the deposits, which is especially useful for research and various geological studies.

In exceptional cases, the sites can be used for educational purposes, provided that the necessary access permits are obtained and that visits take place under proper safety conditions. Active mineral excavations are thus less suitable for use for dissemination to the public, schools, institutions, etc. and require close cooperation between the Geopark and the owners and companies in question - possibly in the form of guided tours.

Increased precipitation will generally affect the groundwater level and runoff conditions in the landscape and locally raise the water level in local depressions, which is a nuisance for cultivation areas with low-lying soils and for low-lying properties. This also applies to existing wetlands and marshlands, of which there are relatively many in the area.

During periods of heavy rainfall, the very rich clay soils on the Stenstrup Issø surface often cause problems with standing water and/or very sticky, soaked soil on the surface, making field work almost impossible.

The majority of the area's landscape is covered in vegetation and/or cultivated, which together with the generally clayey surface layers - despite highly varying terrain slopes - is unlikely to lead to significant changes in surface erosion, even with an increasing frequency of cloudbursts.

A general increase in precipitation coupled with the expectation of future episodes of high precipitation intensity will have some influence on the water flow patterns in the watercourses draining the area, including the Hørup Å-Hundstrup Å watercourse system. In addition, increased leaching of nutrients from cultivated areas in the catchment area may risk increasing the load of unwanted nutrients in the shallow areas around the river's outlet in Nakkebølle Fjord.

Value

The marginal moraine Egebjerg Bakker is one of the most prominent glacial landscapes in the Geopark and, together with Denmark's second largest meltwater lake, Stenstrup Ice Lake and the marginal moraines/dead ice hills around Højes Dong, constitute significant landscape elements in South Funen. In addition, the late glacial deposits in Stenstrup Issø are an important climate archive reflecting past climate fluctuations, which is of scientific, educational and communicative importance in demonstrating past climate variations in relation to the past.