Like the decades before it, fashion in the 1970s changed drastically from the beginning to the end. But the seventies certainly can't be compared to the sixties in that sense.
The 1960s fashion style was still in effect with rebellious hippies and unconventional mods fighting it out in department stores. Seventies fashion was a mish-mash of a bit of everything.
In the end, comfort and casualness won the 70s fashion battle. All looks fought it out over the decade adapting the mod style into a less plastic, simple ease and the hippie look into a tailored chic. Both turned to the use of color; brights for the mods and earth tones for the hippies. As well as bold patterns.
Take a look at these found snapshots from Steven Martin to see what fashion styles of teenage girls looked like in the 1970s.