Figure 3. Time-temperature histories that yield best-fit of predicted results to measured fission-track lengths and ages for Sample 161-95R-2 (Piece 3). A. Ten better fitting results. B. The best-fit run #31, one of 5000 runs modeled using a Monte Carlo genetic algorithm approach (Gallagher, 1995) and the Laslett et al. (1987) apatite track-annealing description. Note that detail in the tT pattern at <60C is unconstrained because no significant track annealing occurs at these temperatures.