The other streams to which Lebanon gives birth flow either from its northern or its western flank. From the northern flank flows one stream only, the Nahr-el-Kebir or Eleutherus. The course of this stream is short, not much exceeding thirty miles. It rises from several sources at the edge of the Coelesyrian valley, and, receiving affluents from either side, flows westward between Bargylus and Lebanon to the Mediterranean, which it enters between Orthosia (Artousi) and Marathus (Amrith) with a stream, the volume of which is even in the summer-time considerable. In the rainy season it constitutes an important impediment to intercourse, since it frequently sweeps away any bridge which may be thrown across it, and is itself unfordable. Caravans sometimes remain encamped upon its banks for weeks, waiting until the swell has subsided and crossing is no longer dangerous.[148] From the western flank of Lebanon flow above a hundred streams of various dimensions, whereof the most important are the Nahr-el-Berid or river of Orthosia, the Kadisha or river of Tripolis, the Ibrahim or Adonis, the Nahr-el-Kelb or Lycus, the Damour or Tamyras, the Auly (Aouleh) or Bostrenus, and the Zaherany, of which the ancient name is unknown to us. The Nahr-el-Berid drains the north-western angle of the mountain chain, and is formed of two main branches, one coming down from the higher portion of the range, about Lat. 34º 20´, and flowing to the north-west, while the other descends from a region of much less elevation, about Lat. 34º 30´, and runs a little south of west to the point of junction. The united stream then forces its way down a gorge in a north-west direction, and enters the sea at Artousi, probably the ancient Orthosia.[149] The length of the river from its remotest fountain to its mouth is about twenty miles.