11. THE HUMBLE BEGINNINGS OF A SOIL 



Upon the pieces of rock chipped from the ledge several plants have gained a foothold. When 

 they die their substance is added to the rocks and other plants thrive thereon 



12. THE GREAT USEFULNESS OK PLANTS AS SOIL BUILDERS 



Leaves, stems, roots all parts of all plants eventually return to the soil, adding to it 

 and enriching it 



