CLASSIFICATION OF LAKE BASINS 117 



Tectonic Lakes, B. Lakes of Construction, C. Lakes of Destruction, 

 and D. Lakes of Obstruction. The further subdivision is as fol- 

 lows : 



A. DEFORALATIONAL OR TECTONIC BASINS. 



1. Fault basins. 



2. Folded basins. 



3. Warp basins. 



4. Complex basins, great basins. 



B. CONSTRUCTIONAL BASINS. 



1. \ olcanic : a. Crater lakes; b. depressions in lava flows. 



2. Chemical : Hot spring and geyser basins. 



3. Organic : a. \^egetal or swamp ; b. coral reef lagoon. 



4. Detrital : ( Reconstructional). 



a. Marine : ( i ) Coastal plain depressions. 



b. Lacustrine. 



c. Fluviatile : (i) River flood plain lakes (oxbows) ; 



(2) delta lakes; (3) fan lakes. 



d. Glacial: (i) Morainal kettle lakes ; (2) drift sheet 



kettle lakes. 



e. Atmospheric: (i) Land-slip basins; (2) dune 



lakes. 



f . Artificial : Human constructions, etc., e. g., built- 



up reservoirs. 



C DESTRUCTIONAL BASINS. 



1. Volcanic: Pit craters, volcanic subsidence hollows. 



2. Chemical : 



a. Solution hollows and sink-holes. 



b. Disintegration hollows. 



3. Fluviatile : 



a. Waterfall lakes. 



b. Pot-hole lakes. 



4. Glacial : Ice excavated rock tarns. 



5. Deflation lakes, or wind excavated hollows. 



6. Artificial excavations : Man-made excavations ; mud 



wallows. 



D. OBSTRUCTIONAL BASINS. Formed by damming a pre- 

 existing valley. 

 I. Tectonic barrier basins. 



a. Warp barrier. 



b. Fold barrier. 



