Overview - Timescale, Physical Landscapes

• 66 - 23 ma
  
• Division of Cenozoic era
  
  Phanerozoic eon
  
  • Paleogene Period
    
    
    • Paleocene
      
      • Danian
        
      • Selandian
        
      • Thanetian
        
      
      
      
    
    
    • Ecocene
      
      • Ypresian
        
      • Lutetian
        
      • Bartonian
        
      • Priabonian
        
      
      
      
    
    
    
    • Oligocene
      
      • Rupelian
        
      • Chattian
        
      
      
      
    
    
    
    
  
  
  

Around 55 million years ago, in the first half of the Cenozoic Era, Greenland and Scandinavia separated and the Norwegian Greenland Sea emerged, connecting the North Atlantic and Arctic Oceans. After that, the Atlantic Ocean continued to expand, while the Pacific Ocean experienced a net decline as a result of ongoing seafloor spreading. The equatorial East-West Tethys Strait linking the Atlantic and Pacific Oceans was greatly altered in the east by the merger of India and Eurasia in the middle Eocene about 45 million years ago, and split in two by the merger of Africa, Arabia and Eurasia in the early Miocene about 18 million years ago. The western part of Tethys broke away from the global ocean system about 6 to 5 million years ago, forming evaporite deposits several kilometers thick in landlocked basins such as Death Valley in present-day California, before becoming the Mediterranean Sea. Antarctica remained Antarctic-centered throughout the Cenozoic, while the northern continents converged northward.