CHAPTER XII. 



THE GREAT RIVER SYSTEMS. 



Rivers Constructing their Own Channels. Varieties of River Tracks. 

 The Mountain Track. The Valley Track. The Plains Track. River 

 Estuaries. Bars. Bar of the Columbia River. Estuaries free from 

 Bars. Great Estuary of the St. Laurence. Inaccessible Estuaries. 

 Process of Formation of a River Channel. Rock-cut Gorges. Chains 

 of Lakes. The Great American Lakes. Niagara. Formation of Alluvial 

 Plains. The Great Plain of Northern India. Evidences of its Fresh 

 Water Origin. Its Vast Extent and Monotony. Flat Gradients of Indian 

 Railways. Results of Borings in the Indian Plains. The Tertiary or 

 Marine Strata underlying it at Great Depths. The Great Plains of Central 

 Asia. Their Gigantic Size and Treeless Character. Area of the Steppes. 

 Steppe Ravines. The Drifting Snows. The Great Indian Plain and 

 the Steppes Contrasted. Water in the Architecture of Nature. Its 

 Rock-cutting Power. The Carrying Powers of Water. Torrents. The 

 Imatra Torrent. Himalaya Torrents and Ravines. Their Vast Depth. 

 Wonderful Gorge of the Indus near Iskardoh. Rise of the Great 

 River Systems mostly in Unknown Solitudes. Their Waters Lost in 

 the Ocean. Classification of Water-borne Debris. Power of Streams 

 Flowing at Various Speeds. Matters held in Chemical Solution. 

 Precipitation. Annual Discharge of Silt by the Thames. Effects of 

 Denudation in the British Islands. Sedimentary Deposits and Formation 

 of New Lands. River Deltas. The River Amazon. Its Navigable 

 Extent. Its Great Tributaries. The Ganges. The Sundarbans. Influence 

 of the Tides in the Ganges Delta. The Ganges and the Bramaputra 

 in the Rainy Season. The Ganges Channel from Benares to the Sea. 

 Causes of the Impetuous Current during the Rains. Water as an In- 

 clined Plain. The Cross Sections of Rivers. The Hooghly at Calcutta. 

 Its Terrible Currents and Shifting . Sands. Accidents to Shipping. 

 Cyclones in the Bay of Bengal. The Nile Delta. The Nile Mouths. 

 Nile Mud. Agriculture in the Nile Delta. The Nile Valley. Central 

 African Lakes. The White and the Blue Nile. The Nile Tributaries 

 of Abyssinia. The Cataracts of the Nile. The Great Nubian Desert. 

 The Caravan Trade. Inundations ot the Nile. Struggle of the Nile 

 with the Desert. Sakiyehs. Es Shaduf. Irrigation Canals. The 

 Equatorial Rains. Progress of the Inundation. The "Lelet-en-Nuktah." 

 Festival of the Letting out of the Waters. The Zone of Perpetual 

 Rains. Torrential Rainbursts in the Zone of Single Rainy Seasons. 

 Great Rainstorm in the Abyssinian Soudan. The River Indus. The 

 Mighty Torrents of the Mountain Track. The Great Gorge at Iskardoh. 



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