GERMAN FOREST NOTES. 8 1 



that the grey sand formation and that of the brown sand, owe 

 their difference to their geological origin. No doubt it can be 

 argued that the difference at present found in the composition 

 of the two varieties of sand may be due to the washing out of 

 the grey sand, and that it is quite feasible that they were 

 originally of the same quality. There is no proof to the 

 contrary, but the theory does not explain the existence of the 

 impenetrable stratum of stones and sand which seems to be the 

 primary incentive to the Ortstone formation. 



Borchgreve asserts that the whole heather area in North-West 

 Germany was at one time covered by forest, and that the present 

 conditions are due to their devastation by the human race. 

 There are clear indications that this was the case, but it does 

 not in any way affect the theory of a different geological origin 

 of the two varieties of the sand formation, for whilst the grey 

 sands were under forest cover the washing out and bleaching 

 process was more or less somnolent, and only became destructively 

 active when the shelter of the forest was removed. 



It has, however, been generally recognised that it should be 

 left to the geological survey to clear up these as yet speculative 

 theories concerning bygone ages, and that it is the clear duty 

 of the practical forester to deal only with present conditions. 

 Now these conditions in the Luneburger heather tracts are 

 normal in the regions of the brown sand, whereas in those of 

 the grey sands they are quite abnormal. 



Albert repudiates the idea that in the latter case he recom- 

 mended the shallow preparation of the soil, which sooner or 

 later would invariably lead to a total failure, or that he 

 condemned the use of the steam-plough under such circum- 

 stances. As a matter of fact, in his final report he strenuously 

 advocates the radical breaking up of the underlying pan, 

 independently of the degree to which the Ort formation may 

 have developed ; such breaking up should include the whole 

 area to be cultivated. This can only be effected by the steam- 

 plough. The old steam-ploughs turned everything upside 

 down and destroyed all adhesion among the various layers 

 of soil. This, however, is almost avoided by the modern plough 

 of improved construction, and the sooner all but the latest models 

 are thrown on the scrap-heap the better. Though this deep 

 rooting up of the soil is under existing conditions necessary 

 and unavoidable, experience has shown that such ploughed up 



VOL. XXIX. PART I. F 



