190 EIGHTH PACIFIC SCIENCE CONGRESS 



longitudes. The coast of East Pakistan lies between 20°-50'N to 22°- 

 50'N latitudes and 89°-00'E to 92°-20'E longitudes. The coast of West 

 Pakistan falls into two distinct divisions: the Mekran coast and the 

 Sind coast. The Mekran coast extends over a length of 350 miles from 

 Hub River, about 20 miles West of Karachi, to Gwatar Bay on the 

 Iranian Border. The coast has a number of bays and is interrupted 

 by two breakwaters. The most important breakwater on this coast 

 known as Miani Hor lies about 60 miles West of Karachi. It is approx- 

 imately 40 miles long and at places 10 miles broad. There are no peren- 

 nial rivers on the coast; all the rivers and streams remain dry except 

 for a few days of occasional rain brought in by the southwest mon- 

 soons during summer and northeast cyclones during winter. The total 

 rainfall on the coast is less than 3 inches a year. Hills, some of which 

 rise up to 3500 feet, are bleak and barren, and run parallel to the 

 coast sloping steeply into the sea. 



The Sind coast extends from Karachi to Sir Creek over a length 

 of 180 miles, and is marked by a network of creeks which extend to a 

 considerable distance inland. These creeks have been formed by the 

 Indus and other rivers as they change course from time to time. Hills 

 are noticeably absent on this coast. 



The coast of East Pakistan is broken by the mouths of the Ganges, 

 the Brahmaputra and numerous other rivers. The 200-mile-long coast 

 is plain except for a fringe of hills on the southeast. These hills are 

 a continuation of the northeastern wing of the Himalayan ranges. 



Beyond the territorial limits of Pakistan lie the waters of the Bay 

 of Bengal in the east and the waters of the Arabian Sea in the west. 

 The floor of the Bay slopes slowly from the shores and the 100-fathom 

 line lies 100 miles from the coast. The bottom topography is smooth 

 except for a submarine canyon directed southward from the mouth of 

 Pusur river. The ocean bottom is covered with thick layers of terrig- 

 enous ooze. The salinity, turbidity and other physical, chemical and 

 biological features of the waters of the Bay are greatly influenced by 

 the heavy discharge of the Ganges, the Brahmaputra and other rivers. 

 The wind movement and revolution of the earth give a rotaiy move- 

 ment to the waters of the Bay. 



In contrast to the Bay of Bengal, the Arabian Sea is open and its 

 waters are subject to influences of the South-East current, of current 

 movements originating in the Mozambique channel and the rotary move- 

 ment in the Arabian Sea. These movements undoubtedly influence 

 the physical, chemical and biological properties of waters of the Ara- 

 bian Sea. The discharge of the Indus also exerts pronounced influence 

 on the character of the water in that part of the Arabian Sea which 



