A little south of Samarra the stony plateau of Mesopotamia ends, and the alluvial plain of Irak, ancient Babylonia, begins.
At the point of entering the alluvial plain the bed of the Tigris seems to be lower than that of the Euphrates, so that the canals run from the latter to the former stream.
A little south of Samarra are found remains of the Median Wall, which stretched south-west towards the Euphrates near Sahlawych, marking the edge of the Babylonian alluvial plain.
Derwentwater and Bassenthwaite occupy a single depression, a flat alluvial plain separating them.
A little below the town of Glarus the river, keeping its northerly direction, runs through the alluvial plain which it has formed, towards the Walensee and the Lake of Zurich.
