RECORDS LEFT BY THE SEA 



A mass of these rounded or egg -like grains all 

 gathered together in a lump is called oolite, from 

 the Greek word "oon" (Latin "ovum"), an egg. In 

 many limestones, now forming parts of agricultural 

 land, this oolitic structure is strikingly shown, and 

 there can be no doubt that in such cases it was pro- 

 duced just as now coral reefs are being formed before 

 our eyes. In the coral tracts of the Pacific Ocean there 

 are nearly three hundred coral islands, besides extensive 

 reefs round volcanic islands. Others occur in the 

 Indian Ocean. Coral reefs abound in the West Indian 

 seas, where in many of the islands they have been up- 

 raised into dry land in Cuba to a height of 1100 feet 

 above the sea-level. The Great Barrier Reef that fronts 

 the north-eastern coast of Australia is 1250 miles long 

 and from ten to ninety miles broad. 



It will thus be seen that, apart from any other con- 

 sideration, the animals of past ages leave permanent 

 records of their existence merely by the accumulation 

 of their dead bodies. Nevertheless, alike on land and 

 on sea, the proportions of organic remains thus sealed 

 and preserved is only a small part of the total popula- 

 tion of plants and animals living at any given time. 



66 



