( 469 ) 
broken and faulted ; elongated tracts of land which took no part in the 
downward movement, so-called “horsten”, (uplifted blocks, “Horste”) 
alternated with tracts which took part in it, so-called “slenken” 
(sunken blocks, “Graben”). 
The trend of these tracts of ground, whose existence has got known 
of late years particularly by the deep borings made by the goverment 
Institute for the geological exploration of the Netherlands is in general 
northwest-southeast in the south-eastern part of the land. 
Moreover it is known that for a great part of the Netherlands 
this subsidence has never given rise to gneat differences of level on 
the surface, because the effect of the sinking was continually more or 
less counterbalanced by ihe accumulation of deposits of sand and silt 
on the sinking blocks. This is proved by jhe fact that the character 
of the fauna of these tertiary deposits down to the greatest depths 
reached until now, continues to be that of a shore or shallow-water 
fauna. 
Without any doubt the depth of the sea was never more than 60— 
70 meters in spite of the great amount of this subsidence. 
We must accordingly assume that in tertiary, especially in late- 
tertiary time the rivers already carried along large quantities of fine 
sediments (sand and silt), towards the North sea in our country as it 
was then, which sediments slowly raised the sinking bottom of the 
sea to such an extent that the accumulation always kept pace with 
the subsidence. As the amount of this subsidence increased towards 
the north-west, the quantity of the sediments deposited in an equal 
space of time had also to increase in that direction, as clearly 
appears from table {. 
The same thing is observed in the east and the southeast of the 
country in the sunken tracts “slenken”. In a “horst” a certain 
formation deposited in a certain space of time can be very thin, or 
may fail altogether, whereas in the adjoining “slenk” the deposits 
formed in the same space of time may have a considerable thickness 
as appears from table II x ). (See p. 470). 
Towards the end of the tertiary period the transporting power of 
the rivers gradually increased, and the amount of sediments deposited 
was consequently augmented. The subsidence of the soil ceased 
temporarily, or was possibly interrupted by a feeble movement in 
the opposite direction. A real or apparent upheaval of the land, at 
all events a negative shifting of the shore line was the result; the 
sea was forced back, and the Netherlands became for the greater 
part, or entirely, dry land. 
1 7~See P. Tesch loc. cit. and Yerslag der Rijksopsporing van Ddfstoffen 1906. 
