584 ENCROACHMENTS OF THE SEA, 
sometimes by artificial means, sometimes by the operation of 
natural causes, and on all these occasions effects were produced 
very similar to those resulting from the formation of the new 
channel in 1825, which still remains open.* Within compara- 
tively recent historical ages, the Liimfjord has thus been several 
times alternately filled with fresh and with salt water, and man 
has produced, by neglecting the dunes, or at least might have 
prevented by maintaining them, changes identical with those 
which are usually ascribed to the action of great geological 
causes, and sometimes supposed to have required vast periods 
of time for their accomplishment. 
“This breach,” says Forchhammer, “which converted the 
Liimfjord into a sound, and the northern part of Jutland into 
an island, occasioned remarkable changes. The first and most 
striking phenomenon was the sudden destruction of almost all 
the fresh-water fish previously inhabiting this lagoon, which 
was famous for its abundant fisheries. Millions of fresh-water 
fish were thrown on shore, partly dead and partly dying, and 
were carted off by the people. A few only survived, and still 
frequent the shores at the mouth of the brooks. The eel, 
however, has gradually accommodated itself to the change of 
circumstances, and is found in all parts of the fjord, while to 
all other fresh-water fish, the salt-water of the ocean seems to 
have been fatal. It is more than probable that the sand washed 
in by the irruption covers, in many places, a layer of dead fish, 
and has thus prepared the way for a petrified stratum similar 
to those observed in so many older formations. 
“As it seems to be a law of nature that animals whose life 
is suddenly extinguished while yet in full vigor, are the most 
likely to be preserved by petrification, we find here one of the 
conditions favorable to the formation of such a petrified stratum. 
The bottom of the Liimfjord was covered with, a vigorous 
*Id., pp. 231, 232. Andresen’s work, though printed in 1861, was finished 
in 1859. Lyell (Antiquity of Man, 1863, p, 14) says: ‘‘ Even in the course of 
the present century, the salt-waters have made one eruption into the Baltic 
by the Liimfjord, although they have been now again excluded.” 
