The Ice Age and Hvalpesøen.
The countryside around Hvalsø is hilly. The station is actually the highest-situated station at Zealand at its 55 meters above sea-level. The hills surrounding the town rise to an altitude of 70-75 meters, yet a lowering in the terrain is seen towards the north-west.
The Mid-Zealand Alps, as they are called, were formed during the last Ice Age, which ended 11,000 years ago. Before that, several ice ages had left their impression the surface for more than a million years with Gyldenløveshøj, the highest point on Zealand, reaching 126 metres above the sea south of the town in the Skjoldenæsholm forest.
The last Ice Age came from the east and covered most of Denmark. Imagine an ice sheet 1 to 2 kilometers high which was moving across the terrain like a bulldozer. The ice pushed a pile of soil, clay, sand and stones in front and put enormous pressure on the ground.
Visible traces can be found in the shape of moraines and subglacial valleys where the snowmelt ran below the ice. The most obvious example of this is the Elverdam Valley, where the glacial stream was heading towards the open sea to the west and north.
The meltwater from the ice cap above Hvalsø ran to the north-west in the Tadre Stream past the watermill at Tadre, now a museum, at its way to the Elverdam Stream, which flows into the Isefjord at Tempelkrogen. Hvalsø is situated close to a watershed as the streams east of Hvalsø run north-east to Borrevejle.
As the ice cap shrank to 50 metres, it lost its ability to move and turned into dead ice with isolated lumps of ice melting long after the cap itself, thus forming the so-called kettle-holes. Avnsø and other small lakes in the Bidstrup forest are examples of such kettle-holes.
There are many forests around Hvalsø, as the uneven terrain was difficult to cultivate. The ice left many stones behind, some with glacial striae, some stemming from as far as Norway and Sweden.
At some sites you may find fossils of sea urchins from the Baltic, which was a subtropical ocean in the Cretaceous period 65 million years ago. The Ice carried the urchins here with other seabed-material and the meltwater sorted the marine sediments in gravel formations.
After glacial times tundra took over, but with the beginning of forest growth the first settlers came to settle in hunter communities. Then followed a more stationary Stone Age community. The first human beings arriving in Hvalsø will probably have seen a much larger lake with cubs of wolf playing along the banks – hence the name Hvalsø.
Where the church stands, there might have been a peninsula jutting into the lake. The changing soil conditions still raise difficulties for house building, for the construction of the local Fakta, e.g., 18 meter bollards were driven into the soil to find solid ground.
The rounded moraines of the area are reflected in the architecture of the sports arena, Hvalsø Hallerne.