( 40 ) 



the figure for /• prol)al)ly l)ec(niie.^ loo ureal as it also hccouics Itv 

 putting' /v'=: 15 mni. 



Pulting (lie aftliix of water at 150 mui. lliis uixes for a surface 

 of 1(S()0() II. A. 27 luillion M'. This auiounl consists of thi-ee 

 parts: J. of what is let in for the liiuhcr lauds l»chiu<l the riiigdvke 

 through vah'es and svphous; 2. of the afllux through ihc ring(l\k(> 

 above (he old sea-ehiv ^vhich I shall call the afllux ////■ii/i(//i ihc alliixiuiii: 

 3. of the aftlux over the whole surface of the polder, uio\iug upward 

 through the old sea-clay oii account of the greater |)i-essure. which 

 1 h^hall call the aftlux /'i-oin the diluvium. 



The lii-st [)art which is no pro[>er afiluw, is estimated l)\ . Mi-. Klink 

 Stekk at 5 to 7 million M' pi'r year. Siilttractiug this and taking 

 the smallest figure the affiux inentioued siih 2 and )) hecomes 22 

 million M^ per year. How much of this is due to each of the parts 

 sub 2 and o cannot be made out, while in those places where the 

 "old sea-clay" is absent no se[)aratioii takes place. Probablv 2 is 

 the greater part, therefore I assume for the [)art sub :> an amount 

 of 10 millioji M-' per year; possibly it is much smaller. 



These 10 million M\ the afllux /'/■oin the diluvium must conseipieiith 

 either How in as fresh water along the circumference of the polder 

 under the old sea-clay through \ht' upper layers of the (lilii\iiiiii, or 

 rise from below as salt water. Let us for the i)reseii( assume that 

 it all tlows to in the former manner. 1ji [\t\y years 500 million M'. 

 of fresh water \vould in this \vay ha\e floured into the dilii\iiiin. 

 Now the quantity of fresh waiter present in the dilii\iiiiu under the 

 Haarlemmermeer [)older i^ ynidtcr ; assuming ^s to 7^ space between 

 the grains of sand this quantity would only correspond to a thickness 

 of 10 metres containing fresh w^ater, whereas this thickness is greater 

 on the average, as is proved e.g. by borings near Sloten. 



The circumference of the ringdyke being about (JO. 000 metres, if 

 we assume the aftlux to take place over a lieighl of only 20 metres 

 and the interstices between the grains of sand to be the same as 

 above, this will give a velocity of motion of 30 metres per year and 

 the water flowed to would, even if we neglect the loss (jf speed 

 further in the polder, have penetrated into the jxdder only 1500 

 metres in 50 yeai's and so not liaxe reached the middle. 



Moreover the assum[)tion thai all the water streaming to is fresh, 

 is not ])robable, if we bear in mind the amount of salt in the Wil- 

 helmina spring which is o\er 1)000 mg. chlorine per litre. Hence it 

 is certain that with a How of 10 million M' fnnn the diluvium, 

 part of the fresh water Jiowadays i)resent in the diluvium under the 



4 



Proceedings Uoyul Acad. Amtitcrdum. Vol. Vll. 



