The extreme ease with which loess is cut away tends at times to seriously embarrass traffic. Dust made by the cart-wheels on a highway is taken up by strong winds during the dry season and blown over the surrounding lands, much after the manner in which it was originally deposited here. This action continued over centuries, and assisted by occasional deluges of rain, which find a ready channel in the road-bed, has hollowed the country routes into depressions of often 50 or 100 feet, where the passenger may ride for miles without obtaining a glimpse of the surrounding scenery. Lieutenant Kreitner, of the Széchenyí exploring expedition, illustrates,[169] in a personal experience in Shansí, the difficulty and danger of leaving these deep cuts; after scrambling for miles along the broken loess above the road, he only regained it when a further passage was cut off by a precipice on the one side, while a jump of some 30 feet into the beaten track below awaited him on the other. Difficult as may be such a territory for roads and the purposes of trade, the advantages to a farmer are manifold. Wherever this deposit extends, there the husbandman has an assured harvest, two and even three times in a year. It is easily worked, exceedingly fertile, and submits to constant tillage, with no other manure than a sprinkling of its own loam dug from the nearest bank. But loess performs still another service to its inhabitants. Caves made at the base of its straight clefts afford homes to millions of people in the northern provinces. Choosing an escarpment where the consistency of the earth is greatest, the natives cut for themselves rooms and houses, whose partition walls, cement, bed and furniture are made from the same loess. Whole villages cluster together in a series of adjoining or superimposed chambers, some of which pierce the soil to a depth of often more than 200 feet. In more costly dwellings the terrace or succession of terraces thus perforated are faced with brick, as well as the arching of rooms within. The advantages of such habitations consist as well in imperviousness to changes of temperature without, as in their durability when constructed in properly selected places, many loess dwellings outlasting six or seven generations. The capabilities of defence in a country such as this, where an invading army must inevitably become lost in the tangle of interlacing ways, and where the defenders may always remain concealed, is very suggestive. [Illustration: Facade of Dwelling in Loess Cliffs, Ling-shí hien. (From Richthofen.)]