28 THE OCEAN RIVER 



the last of the great earth movements began 30 or 40 milHon 

 years ago in the Cenozoic, when the present-day Himalayas 

 slowly rose higher out of the old Sea of Tethys. Part of the 

 new revolution of the land was the modern range of the Appa- 

 lachians, smaller by far than their monumental predecessors, 

 and the present range of the Rocky Mountains. Some 20 mil- 

 lion years later the Alps arose and the great Tethys Sea shrank, 

 until all that now remains of it beyond the Atlantic Ocean are 

 the Mediterranean and Caspian and Black Seas. A final slow 

 heave brought Central America above water and severed the 

 Atlantic from the Pacific, as the Gulf of Mexico began to 

 dwindle to its present size. 



For a while the island of Cuba was joined to Yucatan, and 

 the Ocean River was barred from the path it now takes 

 through the Caribbean. When this connection foundered the 

 Stream poured into the Gulf of Mexico and across the shallow 

 Florida Sea to the Atlantic, and sediments accumulated 

 around the shallow margins of the Gulf of Mexico to a depth 

 of 13,000 feet on what is now southern Louisiana and 5,000 

 feet or more on the future land of Florida. Less than a million 

 years ago, after emerging for a while as an island, Florida be- 

 came a peninsula, and the River was confined in its present 

 course. 



So, for between one and two billion years the Ocean River, 

 its eddies and tributaries, have flowed along their many 

 courses, sometimes branching out to flood places where moun- 

 tains or great cities now stand, reaching out across the entire 

 North American continent to the Polar Sea or to the Pacific 

 Ocean, and across Europe and Africa to China and Malay; 

 flowing where ancient cities were later to flourish and die and 

 where the great Himalayas and Alps now stand. At other 

 times — and today is the most recent of ten or more such 

 occasions — the flow has been restricted to a circular path 

 around the deep Atlantic basin. It has been confined for mil- 



