Handbook of Paleontology 115 



PLANT AND ANIMAL ASSOCIATIONS ALONG 

 THE SHORE 



As has been mentioned in the previous section, 

 shores may be a succession of rocky, sandy or muddy 

 beaches, cliffs, headlands, reefs, open oceans, bays, 

 estuaries, fiords, inlets, lagoons, deltas. The rocky 

 type of shore may have vertical cliffs with deep water ; 

 there may be slopes of varying degree, or reefs may 

 appear. At the base of cliffs may be a mass of 

 boulders ; there may be shingle or sand, or, rarely, 

 mud; sometimes there is a rock erosion plane. The 

 nature of the shore line along a rocky coast depends 

 upon the character of the rock. Igneous rocks tend to 

 weather with a smooth surface and are not suited to 

 attachment. Stratified rocks under weathering give 

 a far better surface, particularly sandstone; and sand- 

 stone of finer structure bears a richer fauna than where 

 the sandstone is coarser. Conglomerates and drifts 

 through weathering give rise to loose detritus that 

 forms shingle banks. Rock-boring organisms are im- 

 portant in the gradual disintegration of rock. Among 

 these are sponges, echinoderms, worms and mollusks. 

 Much depends upon the hardness of the rocks. Sand 

 may be formed from weathering of sandstone or other 

 rocks, comminuted shells etc. It is not always of the 

 same texture or Aveight. It grades on the one side 

 into pebbles and gravels and on the other into muds. 

 Muds likewise show all degrees of variation in texture 

 and composition. Sands may occupy great stretches 

 of the open coast; muds are deposited under more 

 sheltered conditions, as in estuaries, bays, other inlets, 

 mouths of rivers and creeks etc. or farther out in the 



