THE YOUNG NATURALIST. 



247 



The waves act as the agents of disintegration, 

 each one, as it dashes against the rocky- 

 barrier loosens, helps to loosen, or totally 

 removes a few grains of the sand composing 

 the cliff, which will speedily become reduced 

 in size. Angular points and projections are 

 the first to give way, presenting, as they do, 

 a larger space for the action of the water, 

 than the flat unbroken surface of the cliff. 

 Angles disappear, and become rounded. 

 Elevated ridges are often seen running parallel 

 to the dip of the cliff. These are caused by 

 strata of a harder material than the body of 

 the cliff, which are able to better withstand 

 the action of the water. But to what natural 

 use is the waste material applied ? 



It is carried away by the force of the reced- 

 ing tide, and falling to the bottom of rivers 

 and oceans, there accumulates, helping to 

 form treacherous sandbanks and submarine 

 continents. 



Sometimes hugh masses of rock will be 

 loosened by this process, or the action of 

 frost, will fall, and split up into fragments. 



The smaller species will be capable of being 

 moved by the tide, and in their motion, rub 

 against one another, grinding off the angular 

 corners, forming boulders and pebbles. 



These waste deposits gradually accumulate 

 and increase in thickness, forming loose strata 

 on the sea bottom. Many forces tend to 

 solidify these, pressure being the chief. 

 These strata become eventually elevated, and 

 appear as solid masses of rock. During 

 quarrying, the sinking of shafts, and mining, 

 strange animals and plants are found in a 

 petrified state ; gigantic bones and tropical 

 vegetation. Whence came they, and under 

 what circumstances have they put on their 

 present appearance ? They have undergone 

 what is called the Process of Fossilization, the 

 meaning of which I will now endeavour to 

 explain. 



When plants or animals die, the soft parts 

 are the first to decay, leaving in the latter 

 case, the bones or other hard portions. 

 These become gradually covered by sand, 



: dust, earth, or by decomposing vegetable 

 ' matter. They then undergo a gradual change, 

 ! losing their organic substance, which is re- 

 ] placed by mineral particles. This it is 

 J evident that in the course of time, the whole 

 I of the animal or plant remaining will have 

 i lost every particle of its original matter, and 

 become converted into stone, or fossilized. 

 So completely have these fossils lost their 

 1 original substance, that they are often found 

 to consist of a totally different matter to that 

 \ which originally entered into their composi- 

 tion. Thus an Ammonite, -found, in a silver 

 , mine, is composed of pure metallic silver, and 

 : other shells have been converted into iron 

 sulphide. It would seem strange that the 

 ! remains of land plants and animals are found 

 in marine formations, along with the salt-water 

 shells Tercbratula, Astarte, Fusus, Nautilus, 

 and others. It is evident that these animals 

 must have met their death by accident, drown- 

 ng for example; and it is so common an 

 ' occurrence to find whole trees uprooted by 

 the wind, and cast into the sea, that it is only 

 too evident how they come to be found in 

 marine deposits. 



Footprints of annuals are found, chiefly in 

 alluvial deposits, Birds and other verte- 

 j brates, while walking over the beach, leave 

 j the impress of their feet. The intense heat 

 ; of the sun having dried the impressions, they 

 would get filled in with sand or mud by the 

 | next tide, and thus frequently preserved. 

 | Worm-burrows, ripple marks, and rain-pit- 

 ! tings are permanently preserved in a similar 

 j manner. 



■ I before stated how the continents were 

 upraised, the whole of the earth being pre- 

 viously covered with water. The creation of 

 plants followed this. Many four-footed ver- 

 tebrates subsist upon plants, while carnivor- 

 ous animals prey upon herbivorous quadru- 

 peds. Birds are also dependant upon plant- 

 life and insects, while these latter inverte- 

 brated animals could not exist without 

 vegetables. Hence it is plain that the 

 creation, of plants came first. 



