RIVEES OF RIO DE JANEIRO. 



183 



barriers. After receiving the Rio Preto from Itatiaya and the Parahybuna, 

 " Black River," it is joined by the Dous Rios above the S. Fidelis Gorge. 

 Below this point, where it is only 230 feet above sea level, it becomes a navigable 

 stream, winding through rich alluvial plains to the zone of its marshy delta. 



The sediment washed down by the turbid waters of the Parahyba has formed 

 extensive sandbanks north of Cape S. Thome, which frequently shift their position 

 during the floods and storms, and reduce the water at the bar to little over six 



Fig. 75. — MOXTTH OF THE PaRAHTBA AND CaPE S. ThOMÉ. 

 Scale 1 : 1,100,000. 



West or Ijreanwich 



41° 50 



Depths. 



to5 

 Fathoms. 



5 to 10 

 Fathoms. 



10 to 25 

 Fathoms. 



25 Fathoms 

 and upwards. 



18 Miles. 



feet. The Parahyba, a term of doubtful meaning, has a total length of about 600 

 miles, a drainage area of 26,000 square miles, a navigable course of 50 miles, and 

 a mean discharge of 53,500 cubic feet per second. 



On the narrow seaward slopes of the coast range there is no room for the 

 development of any large streams. The Macacu, which enters the north-west side 

 of Rio Bay, although one of the largest, has a course of less than 60 miles. But if 

 the seaboard lacks copious rivers, it abounds in stagnant lagoons and land-locked 

 inlets. South of the Lower Parahj^ba the Lagoa Feia, an old marine gulf now 

 separated from the sea by a strip of sands, has an average superficial area of 170 

 square miles, and communicates through shallow creeks with numerous other 

 lagoons clotted over the low-lying coastLnds. Northwards it is connected, during 



