The second half of the Indus River’s course is as dramatic as the first, but in a different way. Instead of being narrowly confined within walls of mountains, the Indus River spreads itself. Its bed is soon so wide that from one bank the other is invisible. In summer, when the snow and ice melt in the north, the great Indus River, spume and grey, fills its bed to the brim. In winder, when the river is low, islands and sandbanks surface, and the clear water flow in a maze of channels at the bottom of sloping mud-banks.
When the river slows as it must, it drops the silt it has carried through the upper gorges, and its bed gradually rises. In heavy flood, perhaps a glacier dam is breached, or the monsoon arrives before the end of the summer snow-melt, it may charge out of its bed and cut a new channel across the plains.
Only one or two relatively unimportant tributaries flow into the Indus River from the western mountains near Afghanistan at the beginning of its journey across the plains. But halfway to the sea the Indus River is joined by the greatest of all its tributaries from the east, the Panjnad, Jhelum, Chenab, Ravi, Beas and Sutlej. Each has traveled a different path from the Himalaya, uniting only some eighty kilometers (50 miles) before they meet the Indus River.
Below the twin town of Hyderabad and Kotri, the Indus River runs south t o a delta of tamarisks, scrub and saltwater ruses where the great river spreads out in dozens of shallow, meandering creeks and ditches. Sixteen kilometers (10 miles) beyond the coast the Arabian Sea is discolored by the silt of the Indus and beneath its waters a deep canyon marks the channel of the river. The Indus River, cutting through great mountains, driving across enormous sands, carves a last gorge in the sea bed.