A low limestone ridge skirts the Tigris valley from Mosul to Tekrit, and near the Euphrates the country is sometimes slightly hilly; but generally the eye travels over a vast slightly undulating level, unbroken by eminences, and supporting but a scanty vegetation.

The description of Xenophon a little exaggerates the flatness, but is otherwise faithful enough:--"In these parts the country was a plain throughout, as smooth as the sea, and full of wormwood; if any other shrub or reed grew there, it had a sweet aromatic smell; but there was not a tree in the whole region." Water is still more scarce than in the plains north of the Sinjar.

The brooks descending from that range are so weak that they generally lose themselves in the plain before they have run many miles.
In one case only do they seem sufficiently strong to form a river.

The Tharthar, which flows by the ruins of El Hadhr, is at that place a considerable stream, not indeed very wide but so deep that horses have to swim across it.

Its course above El Hadhr has not been traced; but the most probable conjecture seems to be that it is a continuation of the Sinjar river, which rises about the middle of the range, in long.
41 deg.