Notable exceptions of the 1960s were Grace Slick, lead singer of the Jefferson Airplane, Janis Joplin, and Cass Elliott of the Mamas & the Papas.The singer-songwriter movement was only slightly more welcoming, opening the doors for such artists as Carly Simon and Joni Mitchell.A few women crossed over the divide between R&B and rock and again were notable as exceptions, such as Patti Labelle and G