Handbook of Paleontology 79 



The littoral realm (Latin litus (litor), seashore) is 

 composed of the strand and the flachsee or shallow sea. 

 The strand is that portion of the shore included between 

 high and low tide marks and is really a transitional area 

 between the marine and terrestrial realms as the animals 

 and plants dwelling there are exposed to the air twice 

 daily by the recession of the tides. The width of this 

 zone varies considerably, depending upon the height of 

 the tides and the steepness of slope of the strand. It 

 ranges from a few feet in some cases to many miles in 

 rare cases. The flachsee or shallow sea comprises the 

 waters overlying the continental shelf below low water 

 mark and to a depth of about one hundred fathoms. The 

 continental shelf, like the strand, varies in extent, grow- 

 ing in "width at its inner and outer edges. It is formed 

 by storm waves which cut into the shore and deposit the 

 debris and the waste brought down from the lands over 

 this area, particularly at its outer margin. Therefore 

 one would expect to find it widest along old shores or 

 where the coast is sinking, as is the case, and, narrowest 

 along new shores of continents and islands. Because 

 there is plenty of plant food, since light penetrates all 

 parts of this zone, and a substratum, the flachsee is im- 

 portant biologically. The margin of the continental shelf 

 marks the outer limit of the action of heavy storm waves 

 and also the outer limit of the flachsee which is about 600 

 feet below the surface of the sea (100-fathom line). The 

 slope of the continental shelf up to this point is rather 

 long and smooth, but here it descends more or less rapidly 

 to the depths of the sea. 



The pelagic realm (Greek pelagos, open sea) includes 

 the surface waters of the open ocean down to about the 



