The tunnel valley ends with a characteristic fan-shaped area of outwash deposits, the top point of which is at the location of the previous glacier portal. The outwash plain dips gently to the south and underlies Kronhede plantation. Further south and east this outwash plain merges with that formed by Kilen Tunnel Valley (site 14). Together they form an extensive surface that dips gently to the southwest towards Nissum Fjord and the North Sea.
The north-south valley from Lem Vig to the plain at Kronhede was interpreted as a tunnel valley in the early 1900´s, together with many similar valleys that strike normal to the MSL in central Jutland, by the Danish geologist N. V. Ussing (1864 - 1911). He referred to them as “fjord valleys”, a term which was changed to “tunnel valley” by another Danish geologist, V. Madsen. Ussing based his theory on the orientation of many valleys in eastern Jutland that are at right angles to the MSL and end at the top point of fan-shaped deposits at the former location of a glacier portal. From here meltwater spread out and laid down deposits in a fan-shaped area over an outwash plain south or west of the MSL. Ussing considered that the frequent occurrence of the top point of fan-shaped deposits at the end of a valley at right angles to the MSL could not be a coincidence. Another of Ussing´s arguments was that the uneven nature of the long profile of the valleys could not have been produced by a normal stream or river.
Today tunnel valleys, that commonly include a series of lakes, are still interpreted as having been excavated by subglacial streams. The water pressure was sufficient to force the water to flow up hill and out to the outwash plain where its load of sand and gravel was deposited to build a large fan-shaped outwash plain. The detailed dynamics involved in the formation of tunnel valleys are still a topic of discussion among geologists and can be expected to be more complex than outlined here and involve more morphological types. The tunnel valleys in Jutland will therefore continue to be of interest to Quaternary geologists.