“They are made up of range upon range of hills, sometimes with narrow sand-flats and river-beds between; massive hills of giant grey boulders, and others—not nearly so numerous—with rounded summits and a surface of apparent overlappings and downpourings of smooth loose reddish and grey fragments, as if the peaks were of volcanic origin, though no craters are there. But it is the formation of the many hills of giant boulders that make these mountains so astonishing, so rugged, and so unique. You might be on the roughest sea-coast in the world, and not find scenes to surpass them in desolation and utter wildness. They are hills that appear, to the eye, as if a mighty energy underneath had, at some time, heaved and shouldered boulder upon boulder of colossal proportions into position, until large, wide-based, solid masses were raised into magnificent being. On the other hand, there are instances where hills appear as if the forces underneath had built their edifices badly, and in a manner not fit to withstand the ravages of Time; and those are places where part of the pile has apparently collapsed, and there remains a bleak cliff face and the ruins of rocks at the foot.”[7] The slopes and the bastions of the summits of those rugged, gravely picturesque mountains present a sentiment of the sadness that goes with great age; and their dark countenances are the very quintessence of patience. For all time they have stood as over-masters of the Great Desert. Proudly they overlook the far-flung wastes beneath them, where foot-hills die out among black, stony, boulder-strewn plains, and _“lakes”_ of sand, relieved, here and there, by odd-shaped pill-box or church-like kopjes that stand as miniature guardians of the mountains behind them—beyond, right to the faint horizon, nothing but the great dead plains of the desert. Ahaggar is not, as a whole, so rugged and picturesque as Aïr, though it has many similar summits, especially the bare, disintegrating hills of loose brown stone that are rounded and have no pronounced contour. The highest point I reached in Ahaggar was 6,000 feet (near Tazeruk), and in Aïr 6,050 feet (Baguezan). Ahaggar, on the whole, I consider less habitable than Aïr. At the time of my journey, in the months of March and April, the scattered acacias in wadis and mountain valleys were leafless from prolonged lack of rain, and many of them had been completely ruined through natives lopping off all the main branches so as to feed their goats in extremity. Pasturage had completely given out in many places, and herds had left the region to seek grazing ground where life was possible. (Whole families of the _Ehaggaran_ Tuaregs had at that time trekked 500 to 600 miles, to outlying wadis west of Aïr, to keep their flocks and camels alive on _Alwat_, a plant common to some regions, in sandy wadis and among _Ergs_.)