( 475 ) 
pools m which the peat has been formed, and to the bottom of 
which it has sunk, can have been but a few meters deep as a rule. 
How long it is, however, since such a peat layer was formed in those 
pools, is not to be estimated. So we cannot calculate how many 
years this sinking has continued, or to how much it has amounted 
in a thousand years or in a century, supposing it to have been 
regular throughout that time. 
If we consult the opinions of geologists on this subject, we see 
how divergent these opinions are. 
Mr. Staring considers the hypothesis of a sinking in recent times 
improbable, and ascribes the sinking for so far as it has been observed 
here and there, to the pressure of the woods, which have grown on 
the' layers of peat. 
Sues arrives at a negative result for our North-sea and the Baltic-sea 
shores. He is of opinion that visible sinkings were brought about by 
landslips, or by ruptures in not embanked places, or by storms, or 
by climatic changes in the Baltic region. 
Penck does not assume a sinking for the latter part of our present 
geologic period, and does not admit any measurable shifting of the 
coastline for the last thousand years. 
De Geer, too, assumes that the beach in our days is compara¬ 
tively in a period of rest. 
Giinitz adduces some new facts, it is true, which point to a 
sinking, and mentions the formation of the Zuiderzee and the bay of 
the Bollard in the Netherlands, of the Jahde bay in North-Germany, 
the tradition of the Cimbric flood, but does not consider them as 
certain proofs. 
Schucht accepts, indeed, a secular lowering at the time of the 
depositing of the layers of old-alluvial silt and the formation of marshes 
( e - g- of the Weser), but is of opinion that no lowering can be ascer¬ 
tained at the time in which the Dutch range of dunes was broken 
and the conditions of ebb and flood were modified on the Northsea-coast. 
ScHtiTTE thinks that the fact that the seaclay looses its chalk in 
course of time and the silt-layers shrink by desiccation and com¬ 
pression in consequence of the weight of the new silt-layers, 
could bring about at the utmost a time of rest in the lowering. 
Formerly it is true, he thought he could accept a lowering of 
7,5 mm. a year (so 7,5 m. every 1000 years). Afterwards, however, 
be has revised his opinion, and has rejected the grounds for it. 
Dr Reynold estimated the sinking of the ground of the East- 
Frisian Polla rd-polders at 8,8 mm. a year, and Venema l ) has thought 
Venema. Over het dalen van de noordkuststreken van ons land. 
32 
Proceedings Royal Acad. Amsterdam. VqI. XU, 
