f 113 ) 



Then a part of this delta was covered by the northern glacier 

 which deposed its moraines on the surface of the delta. The glacial 

 slicci being retired, a new period begins. The river water remained 

 at the south of the morainal barrier Laren, Rhenen, Nymegen, Cleef, 

 Xanten, and the rivers came from the stadium of the "wild waters 

 into ilif stadium of a compound network. The gravelous diluvium 

 has been deposed and we have to examine in what way thesurface 

 can have heen changed now. 



In the sandy areas which are very numerous in our gravelous 

 (liliviiun. we may expect ; 



<t. the sand which lias I teen removed by the wind. 



//. the sand washed away from the hills by rain water. 



c. the sand deposed by a river in its bed. 



How to distinguish these sands? The sand n must be deposed in 

 a depression and does not show a stratification. The composition 

 and the largeness of the grains do not offer a regularity ami the 

 surface must he hilly. This origin may he possible fur sand districts 

 which are surrounded by gravel-hills. 



The sand c may be found along the rivers or in a groove which 

 represents a faded river bed. In general the surface declines down 

 the current and the sand is stratified in a horizontal position. The 

 composition and the largeness of the grains give no difference in 

 the direction of the stream, neither in vertical direction. 



The sand b may he found in depressions as well as in grooves, 

 has also to show a horizontal stratification, hut in the composition 

 and the largeness of the grains differences may he expected: 



1. in the direction of the groove, when the bordering hills differ 

 in composition, as in the case of the hill- of Holten, Markelo and 

 Lochem. 



'2. in vertical direction. When grains of sand are washed down 

 the hills by rain water, the grains become smaller, while the incli- 

 nation decreases gradually. So the grains of the sand & has to become 

 smaller in the higher parts of the layer. 



The next may show whether this characteristic can practically 

 he used. 



In the last year the Dutch Government drilled at three plae 

 the Peel. As appeared the peat reposes on sand and then the gravelous 

 diluvium follows. The question is whether this sand is a sand l> or 

 a sand c. When the lower parts have indeed a greater quantity of 

 large grains than the higher parts, ii may lie a sand b, else we have 

 better consider it as a sand c. 



