APPENDIX C. 365 



The first mentioned runs from west to east, and the two latter, more 

 or less, from south-west towards north-east. It follows that the 

 forest in the valley of the Schwarzenbach has generally a north 

 aspect, and in the valleys of the Gartenbach and Dobelbach a north- 

 west aspect on one side, and a south-east aspect on the other side of 

 the streams. All the forest areas (except those situated at the highest 

 elevations and which are of no importance) are protected by inter- 

 vening ranges against the prevailing winds. 



Up to a mean elevation of 2,500 feet, .granite is the principal 

 rock, which is sometimes (though rarely) pierced by porphyry. 

 Above the afore-mentioned elevation the granite underlies upper 

 Bunter Sandstein (Yogesen Sandstein), and the latter accordingly 

 prevails in the larger part of the forest area. 



The granite is generally rich in orthoclase and oligoclase, and 

 therefore decomposes readily, and furnishes mostly a deep soil rich 

 in mineral elements. The decomposition is facilitated, and the 

 quality of the soil improved,, by the remarkably numerous springs 

 which appear between the granite and the Bunter Sandstein. Hard 

 slow decomposing quartzite is of rare occurrence. 



The Bunter Sandstein is characterized by rapidly and greatly 

 changing mineral composition, consisting sometimes of readily 

 decomposing - rock yielding a deep clay soil, in other cases of hard 

 quartz-gravel, frequently found on the surface in the numerous 

 boulder-drifts. The Bunter Sandstein has numerous rents and 

 fissures in all directions, so that it is rapidly drained, and the dis- 

 integration and decomposition are only rarely assisted by springs, 

 which at the best are scanty and intermittent. It follows that the 

 Bunter Sandstein soils, even when formed by the easily decomposed 

 and minerally rich clay sandstone, never equal the best quality of 

 the granite soil ; moreover, they change frequently and very sud- 

 denly, and without any visible cause, into almost unproductive areas. 

 On the flat hill tops, layers of fine white sand (produced by the 

 disintegration of the gravelly sandstone) frequently produces an 

 impermeable stratum, preventing the water from percolating, thus 

 causing bogs (or "Grinde") which often extend over considerable 

 areas and are almost unproductive. 



The quality of the soil, therefore, ranges between good and 

 unproductive, in the following proportion : 



Good and fairly good to medium = 78 per cent. 

 Medium to indifferent = 12 



Indifferent to unproductive = 10 



