and you consider them Classic Rock of the 70's???
guess our definitions of classic rock differ then
About the closest thing to a girl rock singer in the 70s, although tending toward new wave. Throw out the folk, disco, metal and pop, and there isn’t much left. Meatloaf had a girl singer, so I guess you can throw his stuff in, as well.
Take a look at the inductives at The Rock and Roll Museum in Cleveland. How many are pure rock groups?
or perhaps our definitions of “mostly” is what differs here