"Amongst the accumulations of Neolithic age which are thought
by many archæologists to be oldest are the well-known
'Kjökkenmödingr' or kitchen-middens of Denmark. These are
heaps and mounds composed principally of shells of edible
molluscs, of which the most abundant are oyster, cockle,
mussel, and periwinkle. Commingled with the shells occur bones
of mammals, birds, and fish in less or greater abundance, and
likewise many implements of stone, bone, and horn, together
with potsherds. The middens are met with generally near the
coast, and principally on the shores of the Lymfjord and the
Kattegat; they would appear, indeed, never to be found on the
borders of the North Sea. They form mounds or banks that vary
in height from 3 or 5 feet up to 10 feet, with a width of 150
to 200 feet, and a length of sometimes nearly 350 yards. …
The Danish savants (Forchhammer, Steenstrupp, and Worsaae),
who first examined these curious shell-mounds, came to the
conclusion that they were the refuse-heaps which had
accumulated round the dwellings of some ancient coast-tribe.
… Shell-mounds of similar character occur in other
countries."
_J. Geikie,
Prehistoric Europe,
chapter 15._