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H. G. Jonker: "B/jdrat/fn tof (Je hninis dr r sedimentaire zrmrfiteenm 

 in Nederland. 



f. De Hondsriu/ in de provincie Groningen, 

 1. Inleiding. Camhrische en ondersilurische zwerf steenend 

 Acad. Proefschrift, Groningen, 1904; Stelling XV. 



First of all this remark. By the //onr/^^r?/// is iisiially meant a ridge 

 extendins; from Groninaen to Emmen in a nearlv N. W.-S. E. direc- 

 tion. It should however not be thought that a perfectly continuous 

 ridge even of but a small height is found here. He who goes by 

 bicycle from Groningen by way of Zuid laren, Gieten, Gasselte, Borger, 

 Odoorn, to Emmen, will freciuently find much difficulty in recogniz- 

 ing the ridge. As then the connection between the elevations 

 which in many places are distinctly to be seen, is not ahvays pei*- 

 ceptible, and the examination of various of those parts has shown 

 a great distinction in structure, it is advisable to be very careful in 

 dealing with conclusions drawn from examinations of one part. 

 Though it may be probable that the origin of the whole Hondsrng 

 is attributable to a single factor, this cannot be adopted a priori and 

 must be proved by comparison of the examination of the single parts. 

 Dubois has examined the southern part of the Hondsrug between 

 Buinen and Emmen, and has drawn conclusions from the observa- 

 tions there, which according to him hold good for the whole Honds- 

 rug and even for the whole region of our Northern provinces. It 

 might be expected therefore that the author had tested his new hypo- 

 thesis bj' previous observations of the region not examined by him. 

 This, however, has not been done; it seems to me that, if he had 

 taken previous researches properly into account especially those made 

 by Van Calki-ui into the Groningen Hondsrug his opinions would no 

 doubt have ])artially changed ^). 



In the first communication — for particulars the reader is referred 

 to the English text, to which the cited pages mentioned below also 

 refer — the author demonstrates that the nucleus of the Hondsrug 

 in South-Drente consists in diluvium of the Rhine, over which the 

 glacial diluvium is pretty regularly spread; on the ridge itself mihe 

 shape of a bed of boulder-sand, seldom attaining a thickness of 1 M.; 

 on the sides frequently as more or less thick banks of boulder- 

 claij. These rather local observations suggest to him the hypothesis 

 that all the land-ice has not reached our country in a direction 

 nearly at right angles with the Hondsrug, but on the contrary 



1) The essay does not mention a single source. It seems to me that this makes 

 it diUicult for the less expert I'eader to form an opinion. 



