FACIES OF THE SHORE ZONE 657 



traction or tension existing among the fine particles of a solid in 

 suspension. These forces are modified by the existence of the salt 

 in the solution. (Whitney-104; Clarke-20.) According to the ex- 

 periments of G. Bodlander (10), the sodium chloride of the sea 

 water is not so important in this respect, other salts, especially mag- 

 nesium chloride, being more active. Carbon dioxide, which abounds 

 in sea water, also rapidly clears it of suspended clay particles, but 

 temperature changes seem to be of little significance in this re- 

 spect. (Kriimmel-55 : 752-57^.) Even in sea water, however, the 

 finest particles do not settle out completely after several weeks of 

 rest. 



Terrigenous muds extend from the shore to abyssal depths. 

 They will be more fully considered under the neritic zone. 



6. Organic fades. 



This consists of the eel grass and peat marsh areas of the sea 

 coast and of the rush and swamp borders of lakes and ponds. The 

 characteristics of these have been fully described in previous chap- 

 ters, and need not be dwelt upon here at length. Extensive mussel 

 beds such as are forming in many places on our sea coast may also 

 be classed here, though these are as a rule intimately associated 

 with the muddy facies of the flats. Shallow-water coral and Litho- 

 thamnion growths are other examples of this facies, which belongs 

 with the lithogenic rather than the lithoclastic division. 



Subaqueous S oliHuction. 



The movement or gliding of rock material when saturated with 

 water, which under subaerial conditions is called solifluction (see 

 Chapter XHI), also takes ])lace under subaqueous conditions. Ar- 

 nold Heini proposed to distinguisii this mode of movement as sub- 

 solifluction (47:7^7). Such movements have occurred in many 

 regions of the world, both on lakes and on the seashore, but only a 

 few cases have been fully investigated. Among these are the glidings 

 which in 1875 and again in 1877 affected the village of Horgen on 

 the Lake of Zurich (Switzerland), and the one which took place 

 in the village of Zug on the Zuger See in the Canton of Zug 

 (Zoug), north central Switzerland. Both of these were described 

 by Professor Albert Heim and others in special publications, and 

 summarized by Arnold Heim in 1908 (47: 136). 



