Souvenirs of the Past

Half a billion years ago there 

was no life at all on the land only

in the warm waters of the seas. And 

even in the sea there were no types of fishes as we know them today. There were only worms snails sponges and primitive crablike creatures. In addition, when these animals died their bodies sank into the silt and of the mud of the ocean floor and the current covered them up with still more mud. Then as thousand and million of years went by the sea bottom slowly hardened into the rock.