IIIFカラー高解像度
国立情報学研究所 - ディジタル・シルクロード・プロジェクト
| |||||||||
|
| IIIFカラー高解像度 |
| Overland to India : vol.2 | |
| インドへの陸路 : vol.2 |
 |
 |
 |
 |
 |
 |
|
|
 |
|
|
|
|
|
|
|
|
引用情報
LI THE SANDY DESERTS OF PERSIA 241
are known in north Africa which have been confined to the same place as far as historical records go back, a conclusion which may be inferred from the names of the wells. Foureau says, in his excellent description of the great Erg 10 in the Sahara : " Dans tous les cas, l'avancement des 1 dunes ou, pour mieux spécifier, l'augmentation de leur volume, ne se produit qu'avec une extrême lenteur, et
di cette lenteur ne peut provenir que de la variabilité du
régime des vents, car si l'on se trouvait en présence d'un
Mi vent régulier, constant, il est certain que l'avancement et
l'accroissement se manifesteraient très rapidement. Il y a
111
donc lutte entre plusieurs aires de vent, et leur résultante
n est que d'intensité faible, ce qui vient prouver clairement qu un vent déplace le travail et modifie le résultat des efforts de l'autre." 1 Foureau concludes that in the region of Africa he visited winds of the southern quadrant are stronger than all the others, and that therefore the movement of dunes takes place towards the north, though
I extremely slowly.
` We find a region of very rapid extension of dunes in
k Eastern Turkestan, where I discovered in the year 1896
two towns entirely overwhelmed in sand, which were abandoned centuries ago, and have since been the object
I of thorough investigation by M. A. Stein. Huntington
I holds that the dunes of Seh-kuheh are only two or three
hundred years old. Walther speaks of small single dunes
F in Turkestan which can move 65 feet in one day during a
le violent continuous storm.
It may often be difficult to detect whether a sandy expanse is moving or not. When northerly winds prevail over the Kevir, one would suppose that the sand-belt on its
i southern margin must move southwards. But such is
certainly not the case. The sandy zone on both sides of Alem is sharply limited on the south, and saxauls grow there on level clay soil on the leeward side of high dunes. To the north the sandhills are said to begin immediately from the level surface of the Kevir, as is also the case north of Aruzun. But if one is on the lee side, that is, the southern, of this sand-belt in a strong wind, one feels the
1 Documents scientifiques de la mission saharienne, vol. i. p. 224.
|
|
|
|
|
|
|
|
|
Copyright (C) 2003-2019
National Institute of Informatics（国立情報学研究所）
and
The Toyo Bunko（東洋文庫）. All Rights Reserved.
本ウェブサイトに掲載するデジタル文化資源の無断転載は固くお断りいたします。