beyond it, 2024. The farther down we go the greater becomes the distance between the lowest parts of the basin and the terraces.
That the basin of the Desht-i-Lut was also a lake-bed during a damper climate is beyond doubt ; and all the more because it borders on Seistan, and is separated from it only by a rather low system of hills. The causes which made the Hamun to attain an incomparably greater depth and a more extensive area must also have affected the Desht-i-Lut, which is an enclosed basin receiving a considerable number of streams from the surrounding hills. On the road along its northern edge are passed manifold drainage channels of large dimensions, out of all reasonable proportion to the present precipitation of the country. Similarly all the numerous basins without outlets which are to be found in Persia, many of which still contain temporary lakes or salt sheets deposited in lakes, were formerly the beds of larger or smaller lakes. Undoubtedly many of them have been connected over sills that still rise slightly above the floor of the kevir beds.
On the accompanying map of Persia the limits of the great Kevir are laid down as determined by Vaughan, myself, and others. But when the basin was full of water, and the lake attained its maximum, its shore was in quite a different position to the present margin of the Kevir. On the whole, the contour of the lake was parallel to the border of the Kevir, but lay outside it ; the lake had a larger area than the Kevir has now. The transforming forces on the earth's surface labour in increasing the distance between these two lines. The detritus fans and weathering products of the hills are swept down, and move on over the level ground of the Kevir. These forces are of exactly the same kind as during the damp period when the great lake existed, but they are incomparably weaker in the dry period now prevailing. The coarser material carried down after heavy rain by brooks and floods are deposited on the detritus fan ; the finest material, silt, is carried as before out into the Kevir. Therefore, it is a natural consequence that the floor of the Kevir lies higher on the edges than in the middle.
IIIFカラー高解像度
