In and around Amersfoort lots of nature can be found. The city of Amersfoort is beause of that located at a very special place. Three different landscapes join here together: The 'Utrechtse Heuvelrug', the 'Gelderse Vallei' and the 'Eemland'.
Lots of the natural relief is originated during the the penultimate glacial period, the Saalien (200.000 - 125.000 years ago). A thick layer of ice covered the largest part of the Netherlands. From the north the ice spread further to the south. Big ice lobes pushed their way, through the river valleys, further inland. By the pressure of that ice the river beds were pushed upwards.
That way long stretched ridges originated (called 'Stuwwal'). As probably known, the 'Utrechtse Heuvelrug' is such a ridge ('Stuwwal') and the 'Amersfoortse Berg' is a part of the 'Utrechtse Heuvelrug'. The ice masse pushed the ground on the place around Amersfoort tens of meters up. The highest point is located at the 'Leusderheide' (55m). But also the 'Amersfoortse Berg' is quite high. Calculated from the New Amsterdam Level (NAP) it measures 42.5 meter (keep in mind that the Netherlands is a flat country with its highest hill just measuring over 300 m!).
Just after the penultimate glacial period this mountain (hill) must have been a few meters higher, and should have given a stunning view over the nearby sea. The 'Gelderse Vallei' melted and the enormous amount of ice changed into an inner sea. The climate during that period in time was extremely pleasant. In the neighbourhood fossils have been found of shells the we find nowadays on the beaches in the south of France.
Dunes and Streams
After the warmer period, from 125.000 - 90.000 years ago, the last glacial period, the Weichselien, (90.000 - 10.000 years ago) followed. During this ice age the ice caps did not reach the Netherlands, but the ground is permanently frozen (permafrost), resulting is almost no growth of plants and trees.
The hard winds blew the top layer sand of the 'Utrechtse Heuvelrug' into the 'Gelderse Vallei'. The height of the mountain (or hill) became much less. The top layer of the sand that blew into the 'Gelderse Vallei' stopped and grew at irregular places. This resulted in the formation of Dunes. These higher parts (or dunes) are called 'dekzandruggen' (freely translated 'top layer sand ridges'). Lots of these 'dekzandruggen' can still be found in and around Amersfoort.
In the lower parts between the 'dekzandruggen' the streams flowed, it was wet and swampy. All the water in the valley streams towards Amersfoort. At the lowest point all streams come together and they go further as the river 'De Eem'. At the spot were the river 'De Eem' could be crossed, the city of Amersfoort originated.