Volcano üshima, Idzn. 47 



consequently the lavas could flow out through this eastwards, thus 

 affording an additional factor for the abnormal development of the 



eastern slope. 



(d) Another cause for the development of the abnormal to- 

 pogi-aphic features on the eastern flank may be wind action on 

 the dry surface of the caldera. The effects of winds now in 

 operation and actually recognizable are by no means small. The 

 inside of the caldera is tliickly covered by loose éjecta (volcanic 

 ashes, sands, lapilli, bombs, lava-blocks, etc.) and by fragmental 

 materials produced by friction or by other destructive actions. The 

 effects of the winds on . this dry surface is considerable. The 

 sand- worn blocks, some of which are three faceted in the form of 

 " Dreikanter ", lying in the caldera, and various marks on the sandy 

 surface show the abrasive effects of wind-blown sands. These 

 marks indicate the direction of the prevailing wind in the caldera. 

 Feather-like patterns marked on the surface of an aerial volcanic 

 sand bed at the northeastern brim of the central crater show the 

 direction of the wind to be N.E. to E. by N., while the patterns 

 marked on the loose sandy surface at the northeastern part of 

 the caldera by the sorting action of the wind (according to the 

 size of the fragmental materials) show it to be N. l}y E. to due 

 E. That the finer particles are found accumulated on the lee side 

 of large blocks is an indication of the strength of the winds. The 

 eastern slop 3 of the volcano is thickly covered by sands and lapilli 

 transported by the winds from the caldera through the great eastern 

 gap of the encircling wall. 



Although the effect of each of the above may be comparatively 

 slight, yet the writer believes that taken together they may be 

 sufficient to cause the abnormal feature of the eastern slope. 



