THE ZURICH WOODS. 35 



The aspect for the most part is north-east. Not less than 

 twenty-two tiny rivulets — sometimes mere dry channels, but 

 at other times swollen into dangerous torrents — abruptly divide 

 the main bank into smaller sections. Against the erosive effects 

 of these streams Herr Meister, who controls the forest, is taking 

 energetic measures, and as he is doing so by means of various 

 devices, many useful lessons are provided even in this con- 

 nection. The gradient is steep in places, but it is found that 

 where the slope is under 36°, forest canopy is still possible. 

 Beyond this, however, there is difficulty, and the Forstmeister 

 places the ordinary limit for satisfactory tree-growth at about 42°. 



The soil of the greater portion of the area is of a marly 

 nature, overlying Keuper sandstone (Triassic). This is easily 

 eroded, and the tendency is for the smaller water-courses to 

 deepen their channels, and to cause subsidence of soil from 

 the sides. The lower ground near the river Sihl is comparatively 

 level, and consists of a tenacious clay with some loam in it. 

 On other parts of the area diluvial soils have been deposited, 

 and there are also moraines in places. Speaking generally, 

 the soil is of excellent quality for the growth of trees, but its 

 productivity is chiefly due to the long continued, careful 

 management of the forest. One cannot help thinking that, 

 under the management generally given to land of this descrip- 

 tion in Britain, the area would have yielded very much poorer 

 results. Were the Sihlwald not cared for in quite a special 

 way it would deteriorate remarkably fast. Instead of being 

 neglected, however, the forest resources are husbanded with a 

 watchful regard such as might be bestowed on a market 

 garden. Labour is not cheap, nor is it lavishly applied to 

 the forest : it is rather that the treatment is so intensive and 

 so scientific that nothing is allowed to lie waste or deteriorate. 



Careful investigation has been made in regard to the nature 

 of the soil. Professor Schultze, of Zurich, finds that where 

 the largest proportion of fine particles exists, the "quality of 

 the locality " is highest and the land is most productive. This 

 practically means that within bounds, and under the conditions 

 which obtain at Sihlwald, the higher the proportion of clay, 

 the greater is the fertility of the soil. 



As to the mineral matter in the soil, it has been found that 

 lime plays the most important part in determining productive 

 capacity. In the first or best class of Sihlwald soil there is 



