Key periods of time in the history of American superhero comic books have been given different names: Platinum Age (1897-1937): This is the pre-superhero era of comics with content consisting mainly of funny animals and political cartoons. Golden Age (1938-1955): This period started with Superman in Action Comics #1 and gave birth to some of comics most famous characters like Superman, Batman and Captain America. Silver Age (1956-1969): This period started with the publication of DC Comics' Showcase #4 and the modern version of the Flash. Spider-Man and the X-Men were also created during this period. Bronze Age (1970-1983): Comics produced in this period started to tackle issues of social injustice. Copper Age (1984-1991): "Comics aren't just for kids!" was the slogan of the 80s, with seminal works such as Watchmen, The Dark Knight Returns, and Sandman. Modern Age (1992 – present): Also known as the Dark Age as superhero comics produced in this time period became more grim, but also branched out in new directions following the near collapse of the industry in the 90s.