Overview - Timescale, Physical Landscapes

The Cambrian was named by British geologist Adam Sedgwick in 1835 for the slate succession in south Wales and southwest England. These rocks contain the earliest records of abundant and diverse life forms. The period and phylogenetic names are derived from Cambria, the Roman name for Wales.

• 541 - 485.4 ma
  
• Division of Paleozoic era
  
  Phanerozoic eon
  
  • Cambrian
    
    • Terreneuvian
      
      • Fortunian
        
      • Stage 2
        
      
      
      
    • Series 2
      
      • Stage 3
        
      • Stage 4
        
      
      
      
    • Miaolingian
      
      • Wuliuan
        
      • Drumian
        
      • Guzhangian
        
      
      
      
    • Furongian
      
      • Paibian
        
      • Jiangshanian
        
      • Stage 10
        
      
      
      
    
    
    
  
  
  

In Laurentia, a significant drop in sea level during the Late Cambrian is suggested by the loss of some fauna and a single unconformity that defines the boundary between the Dresbachian and Franconian facies, two regional facies found in the peripheral regions of North America.

Cambrian volcanic activity has been detected in several regions. Australia is particularly active, with large areas of northern and central Australia covered by flood basalts in the early Cambrian. Basalts and mafic intrusive rocks in southeastern Australia formed in volcanic island arc environments during the Early-Middle Cambrian. Volcanic rocks of similar age occur in New Zealand and parts of Antarctica.

Large-scale tectonism during the Cambrian and early Ordovician affected large areas of what is now Gondwana in Australia, Antarctica and Argentina. At least some of the above volcanic activity, especially on volcanic island arcs, suggests that seafloor spreading and tectonic subsidence were active geologic processes.