e form of the structures that were down below, such as
quadrangular buildings, walls, domes, etc. It was not the natural
formation of sand on a natural ground. In one particular place a whole
city wall with towers could be traced, just showing above ground, so
perfectly rectangular that although covered by sand it would seem certain
that a fortress must be buried under this spot.

All around these particular suspected buried cities the sand is
absolutely flat, and there would be no other plausible reason for this
most extraordinary irregular accumulation of sand reproducing forms of
walls, domes and towers against all the general rules of local sand
accumulations, unless such obstacles existed below to compel the sand to
accumulate in resemblance to them. This theory is strengthened too by
the fact that, here and there, some of the higher buildings actually may
be seen to project above ground. The sand mixed with salt had, on getting
wet, become solid mud, baked hard by the sun.

Anybody interested in sand and its movements, its ways and process of
accumulation, could not do better than take a trip to this part of
Sistan. Little as one may care about sand, one is bound to get interested
in its ways, and one point in its favour is that with a certain amount of
logic and observation one can always understand why it has assumed a
certain formation rather than another--a pleasing feature not always
existing in all geological formations of the scenery one goes through.

The great expanse of irregular surface soil, with its innumerable
obstacles and undulations, was, of course, bound to give curious results
in the sand accumulations south of it, where the sand could deposit
itself in a more undisturbed fashion and was affected by purely natural
causes. Of course, sand hills do not accumulate in the flat desert unless
some obstacle--a mere pebble, a tamarisk shrub, a ridge, or a stone, is
the primary cause of the accumulation. In the present case, I think the
greater number of sand hills had been caused by tamarisk shrubs arresting
the sand along its flight southwards.

To enumerate and analyse each sand hill--there were thousands and
thousands--would take volumes. I will limit myself to the various most
characteristic types of which I give diagrams. The absolutely conical
type was here less noticeable, being too much exposed to the wind, which
gradually corroded one side of each hill more than the other.

Whatever their s