Digging without cards
You cannot dig unless you have at least 1 point of specialized knowledge in that region. From the rules, page 5:


  If the player fulfills the requisites below, he can execute an excavation.
  
  The minimum requirement
  
  
    • The player has a valid excavation permission for the area.
    
    • The player has at least 1 point of specialized knowledge for the excavation area, either from a researcher card or found item.