Semimajor axis (a), apocenter distance a(1 + e), and pericenter distance a(1 − e) vs. time of Jupiter (pink), Saturn (dark purple), Uranus (blue), and Neptune (light purple) along with the time and location of collisions with test particles for Uranus (blue triangles) and Neptune (purple stars) during the initial chaotic period. The first row shows simulations in which Neptune starts and ends exterior to Uranus (No Swaps 1&2), while the second row shows simulations in which Neptune starts interior to Uranus (Swaps 1&2).