How would you explain ‘Rock of Ages’ in the context?
Mother and I met the important friends in a restaurant. Waitresses in long, striped skirts brought carts of rainbow-colored juices: pomegranate, pineapple, guayabana. The Important Friends paid no attention to the pretty juices, discussing the federal investment plan and why the Revolution will fail. Mother wore her smartest silk chiffon, a blue helmet hat, and ear drops. Her son wore a dress coat too tight and short. Mr. P. T. Cash wore his Glenurquhart plaid suit and nervous expression, introducing Mother as his niece visiting for the year. The friends were oil men with oiled hair and one old doctor named Villaseñor. His wife, a Rock of Ages in high lace collar and pince-nez. All gringos except the doctor and wife.
How would you explain ‘Rock of Ages’ in the second to last sentence?