The opposite of uniformitarianism is occasional catastrophic trigger. The process of erosion pulls the trigger for sudden deformation. Slow deformation pulls a trigger for eruption. Eruption triggers internal intrusions. The Frank Landslip; the Charleston, San Francisco, and Napier earthquakes; the Pelée eruption; and the Yakutat upheaval all created terrific surprises for geologists. The gigantic intrusions through millions of years from the core of the earth, made of white hot star matter, percolating to surface volcano belts up 1,800 miles of permanent, primitive cracks, are mostly balanced by the crustal weight. This is the adjusting globe. But the intrusive mechanism, under tides in the rock and in the oceans, always in motion, pulls the trigger for the big geologic revolutions. The very deep broken earth blocks shift, volcanism between them heats the surface, floods the surface with gas foam, and lifts areas of surface by heat swellings; and on the surface, what was a glacial period gives place to a volcanic period. The last of these was the Miocene Tertiary, with large-scale volcanic eruptions all over the world. Comparing Boston with the Black Hills showed underground eruptions in the latter, for which a warping uplift pulled the trigger. These were the rock cisterns or lenses of porphyry injected among the strata. The time of this was Miocene or Eocene Tertiary, probably later than most of the volcanoes of the Yellowstone, farther west. Boston, on the other hand, was making black basaltic dikes, probably identical with the volcanoes of the Berkshire Hills and New Haven, of the age of the big reptiles, 150 million years before the Black Hills injections. The trigger which pulled off the Boston eruptions was the Appalachian warping. That which fired off the Black Hills was the Laramie revolution that pushed up the Rocky Mountains. The injection of lava lenses in the Black Hills was a form of deformation of strata which we experimented with in the laboratory. The layers of sandstone, limestone, and old ocean muds covering over the arch of these hills were injected by dikes or fissure fillings from below. How would injections behave? With Ernest Howe as my associate, I arranged a square tank for sedimenting sand, plaster powder, coal dust, or marble dust in layers under water. Under it was an iron cylinder in which wax could be melted. A screw piston pushed the molten wax up to inclined or upright slots in the middle of the tank box. The water was drained off, and the hot wax was injected up into the strata. The tank sides were taken down, and hardened lenses of wax were sliced vertically with a hot knife to show what had happened to the strata by the process of wax intrusion.