248 Forestry Quarterly. 



survived through the claimed four glacial periods and that other 

 species returned again only in a different mixture from that 

 in which they used to occupy the valleys, during other glacial 

 periods. 



It is also believed that valleys have changed considerably in 

 the last period, after the pressure of the ice that caused falling 

 of mountains had ceased, and that the lateral moraines have 

 been carried down the hillsides, and the re-establishment of 

 forests has crowded the avalanches into their present localities. 

 As the population increased and men were depending on the cattle 

 ranges in higher altitudes they soon commenced to get wise and 

 learn to build their homes on other places, as below the forests, 

 on hills, etc. But the forests can give protection only as they 

 remain in closed stands which is best secured if interference 

 by man is prevented. This led to the creation of "Ban For- 

 ests" or protection forests as early as in the year 1342. Since 

 that time protection forests have been made wherever the ne- 

 cessity for them existed, and no less than 322 copies of proclama- 

 tions of Ban Forests are in the possession of the Protective 

 Service of Switzerland comprising the periods from 1535 to 

 1777. These forest reservations were created, but nothing was 

 done for their future. Grazing of sheep and cattle continued, 

 litter was taken, reproduction commenced to fail, old stands de- 

 teriorated and became too open to afford sufficient protection. 

 After a hard fight with the cattle and sheep owners, ban for- 

 ests were brought under a systematic forest management These 

 forests are managed under the selection system in horizontal 

 strips. 



The construction works of early ages were merely of a defen- 

 sive nature, restricted closely to the object to be protected, and 

 consisted of walls erected in front of churches and houses with 

 the object of dividing or breaking the avalanches. At the be- 

 ginning of the ninteenth century more radical methods were 

 employed against the attack of avalanches in their "status nas- 

 cendi." The construction works for the prevention of avalanches 

 are divided into works which are confined to the starting point 

 and those which are for the purpose of deflecting the slides 

 from objects of special protection. To the first, the most im- 

 portant group, belong all those which increase the friction be- 



