34 



EARTH FEATURES AND THEIR MEANING 



Sedimentary. Laminated 

 and with rounded 

 grains. 



rSubaerial. Sands and loess. 

 Subaqueous. (See below.) 

 Glacial. Coarse, unstratified deposits with 



faceted pebbles. Till and tillite. 

 Fluvio-glacial. Stratified sands and gravels 



with "worked over" glacial characters. 



Metamorphic. Schistose {Metamorphic proper. Due to below surface 

 and with grains either ! changes, 

 angular or rounded. [Residual. Disintegrated at or near surface. 



Subdivisions of the sedimentary rocks. While the eolian 

 sediments are all the product of a purely mechanical process of 

 lifting, transportation, and deposition of rock particles, this is 

 not always the case with the subaqueous sediments, since water 

 has the power of dissolving mineral substance, as it has also of 

 furnishing a home for animal and vegetable life. Deposited 

 materials which have been in solution in water are described as 

 chemical deposits, and those which have played a part in the life 

 process as organic deposits. The organic deposits from vege- 

 table sources are peat and the coals, while limestones and marls 

 are the chief depositories of the remains of the animal life of the 

 water. The tabular classification of the sediments is as follows : 



Mechanical 



Classification of Sediments. 



Subaqueous 



Deposited by water. 

 Subaerial or Eolian 



Deposited by wind. 

 Glacial 



Deposited by ice. 

 Fluvio-glacial 



Conglomerate, sand- 

 stone and shale. 

 Sandstone and loess. 



Till and tillite. 

 Sands and gravels. 



Chemical 



Organic 



Glacier-water deposits. 



Calcareous tufa Deposited in springs 



and rivers. 



Oolitic limestone Deposited at the 



mouths of rivers 

 between high and 

 low tide. 



("Formed of plant re- Peats and coals. 



mains. 



I Formed of animal re- Limestones and 



I mains. marls. 



