(Leinster's  historical model is  the recurring Gold Rush of the Nineteenth Century, drawing adventurers in 1840s from the settled East Coast to wild California, and in 1890s from settled California to the wild Klondike.)
Leinster's historical model is a recurring pattern of Gold Rush, drawing adventurers from settled areas to remote locations, with two distinct periods: the 1840s East Coast to California and the 1890s California to Klondike.