From lake Ferring Sø the terrain gradually rises to Bovbjerg lighthouse that is 40 m above sea level. Lake Ferring Sø is a depression and Bovbjerg lighthouse is located on top of a terminal moraine. The gradual slope up towards the top of the terminal moraine is disturbed by a series of small east-west ridges that are equivalent to glaciotectonic thrust sheets in the cliff. The terminal moraine extends for about 1 km south of the lighthouse where it abuts an outwash plain. This boundary between the terminal moraine and the outwash plain marks the MSL. The precise location of the line is not clear when you are standing on the top of the cliff, but it is where there is a change from clay-rich soil to sandy soil. South of the stream Dybå the land rises to the hill island of Fjaltring Bakkeø, deposits of which can be seen in the cliff at Fjaltring.
The coastal cliff at Bovbjerg represents a continuous profile that reveals the structure of the landscape and the composition of its components. The northern part of the profile, from Ferring to just north of Bovbjerg lighthouse, is not so well exposed but consists dominantly of clayey till. The central part of the terminal moraine, about 200-300 m north and south of the lighthouse, is strongly deformed. Outwash sediments and moraine deposits have been folded and faulted into glaciotectonic thrust sheets. The thrust sheets strike east-west and dip to the north, corresponding to formation by ice pressure from the north. The thrust sheets were emplaced during advance of the glacier that formed the MSL. After up-thrusting the sheets were overrun by the ice which has deposited a layer of basal till over them.
Some distance south of the lighthouse, where the cliff exposures are excellent, the layers are again close to horizontal. About 1 km south of the lighthouse the MSL is clearly visible in the cliff where the uppermost till layer wedges out and disappears (Fig. 1-3). South of the MSL the cliff consists dominantly of sand and gravel meltwater deposits, but at Fjaltring there is a low cliff with, amongst others, clayey meltwater deposits. Historically this stretch of coast has been subjected to powerful erosion (see site 37 – The West Coast). The coast is now protected by a series of groynes and erosion has subsequently decreased, but it is still adequate to keep the profile open. From one year to the next there can be major changes to the profile because of landslips - especially as a result of storms and high water levels. Interesting elements of the landscape along the cliff are several marked erosional gullies (Fig. 1-4). These were originally formed by large landslips but have become the course for running water (seepage of groundwater or drainage) that has eroded deep into the soft sediments. This kind of landscape is unique in the geopark and is seldom developed in low-lying Northwest Europe.