( M-2 ) 



basall nol being considered as a mixture of minerals, il would be 

 concluded that these sands belong to a glacial sheet which hail 

 reached our country before the gravel of' the Rhine-diluvium had 

 been deposed. Such a contradiction would give rise to mam difficulties. 



There is still more. In the gravelous diluvium in situ, the practical 

 limit of <*,4 " „ will probably give good results, luit in the "zand- 

 diluvium", the materials of which must have been derived from the 

 gravelous diluvium, the quantity of heavy minerals must have been 

 changed, according to the different manners of derivation. Here the 

 greatest prudence is wanted. 



When a characteristic can be pointed tint which may be considered 

 as the. effect of these different manners of derivation, a further step 

 has been made. I believe I have found a specific which may aid in 

 some cases to take a decision, where the rules of Schroeder van 

 der Koi.k (hi not help. 1 add immediately that this specific is noj at 

 all universal. 



Il will be necessary to tell in a very general manner how in my 

 opinion the beginning of the diluvial period found our country and 

 how our gravelous diluvium has heen deposed. 



As much as we know now, the tertiary base of our country is 

 marine excepted Sonth-Limburg). In the western pari of Zeeuwsch- 

 Vlaanderen the base is formed by the "rupelleem", in the eastern part 

 ii is the marine deposit of the Diestien. Along our sou l hern frontiers 

 the marine deposits of the Poederlien, Diestien and Bolderien exist. 

 The sands of the Moséen appertain in my opinion to the old fluviatile 

 diluvium. The miocene land- and fresh-water deposits seem to be 

 restricted to South-Limburg. Along our eastern frontiers the base is 

 formed bj npper-oligocene sea-sands, to the north these strata are 

 covered by miocene deposits. In Gelderland and Overyssel the same 

 miocene cla\ forms the surface. In North-Brabant and North-Limburg 

 this miocene is still covered by sands which probably appertain to 

 the pliocene. To the north and west I.ouik has shown a pliocene 

 sea-ground at several places Grave, Arnhem, Goes, Gorkum, Bergen 

 op Zoom. Utrecht and Amsterdam which declines to the north- west. 

 So ai the beginning of the diluvial period the greater part of our 

 country was covered by the pliocene sea and only in the east and 

 south-east a coast existed. 



Now the rivers Rhine ami Meuse supplied the enormous quantity 

 of sand and gravel which form everywhere in our country the base 

 (excepted Zeeuwsch-Vlaanderen and South-Limburg). A delta was 

 built which tilled up the basin of Holland and the Southern Xorlli- 

 sea as far as the chaik rocks of Norfolk and Suffolk. 



