"Rampant youth"

Often I have wondered how I, “missing so much and so much,” made it through this far. It was bad enough anyway but during the years I wrote my books, such as they were, I might as well have been hit on the head and put into deep freeze. I remember how surprised I was when I took my niece and some other guests to the one concert by the Beatles in Oregon during their one and only tour of the nation. We took our seats early, and as all this rampant youth poured in, I couldn’t believe my eyes at their clothes and shoes and here were all these bales of hair grown while I was sleeping. Who were these people? Where had they come from? And so it has been.
     --From Ardyth's memoir New York on Five Dollars a Day