National Institute of Informatics - Digital Silk Road Project
Digital Archive of Toyo Bunko Rare Books

scarcely necessary to point out that the use of these distinctions can serve only for approxi-
mate guidance.
Here I may conveniently mention that for quasi-technical reasons, names, usually end-
ing in -jilya (Turki), indiscriminately applied both to streams and the
Lettering of temporary valleys containing them, have always been printed in blue without re-
water-forms. gard to whether the streams generally carry water or not. For the
same reasons the lettering of all temporary water-forms, such as flood-beds, seasonal marshes,
etc., has been shown in blue.
Marshy areas, being subject to considerable seasonal changes in arid regions, such
as those represented by most of the maps, introduce a special element of
Representation of uncertainty into cartographical representation. I have tried to restrict
marshes. the use of marsh symbols in blue to ground which is likely to be covered
with water for the greater portion of the year. But it should be remembered that where
drainage beds, ordinarily dry, terminate in areas shown as sandy tracts with living desert
vegetation (reeds or scrub), extensive portions of the ground are likely to be found boggy
during the season of spring floods from the melting snows of the mountains. ²
Salt-encrusted areas, marking dried-up lake-beds and marshes or ground subject to
inundation or percolation at intervals followed by evaporation, form
Salt-encrusted areas. very important features of the surface in the lower portions of the Tārim
basin and of the adjoining drainageless regions. They date from differ-
ent periods and present considerable geographical or geological interest. I have accordingly
thought it desirable in the course of our later surveys to distinguish areas showing marked
differences in the salt formation covering their surface.
Three varieties of new symbols have been introduced for this purpose, all derived from
the conventional symbol in use for water of lakes and marshes, but all
Varieties of salt shown in black. Thin lines with hook-like ends turned upwards on the
symbols. right indicate a crust of hard salt, practically pure, crumpled up into
hummocks or small ridges, such as covers the greater portion of the ancient Lop sea bed.
The crust of salt-permeated clay, usually formed into big lumps quite as hard as the first
variety, and usually found near the edges of ground still receiving some water, has been shown
by similar lines with hooks turned downwards on the left. Finally, ground where a soft crust
of salt of varying depth covers the underlying soil is indicated by lines with downward hooks
on the right. ³ Ordinary salt efflorescence (known as in India by the term shōr) is present to a
greater or less extent almost everywhere in the Tārim basin where subsoil drainage comes to
the surface or temporarily inundated areas are near; it has hence not been specially marked.
Among other permanent surface features drift-sand is the most important in the
regions represented by the majority of the map sheets; for it covers
Representation of the greater portion of the Tārim basin. For drift-sand bare of vege-
drift-sand. tation, or nearly so, brown stipple has been used. The indication of
dunes within areas of bare drift-sand by small clusters of thicker stipple facing to the south-
west is meant to be purely conventional. It has been chosen with regard to the prevailing
wind direction, though the bearing of individual dunes varies greatly in different desert
areas. But where large accumulations of dunes in the shape of high ridges or dawāus are
met with, usually near river courses or parallel to them, they have been shown with the true
bearing of their axis as actually surveyed. ⁴
Two surface formations of desert ground often associated with drift-sand are of
sufficient importance to claim representation by special symbols. The
Representation of one adopted for yārdangs or wind-eroded clay ridges and trenches, so
yārdangs and 'Mesas.' characteristic of different parts of the Lop depression, shows a form
meant to represent the usual bearing of the ridges from N.E. to S.W. and their tail-like end
tapering to S.W. For the high clay terraces or 'Mesas' also due to erosion but of earlier