"Mainstream geology is founded upon enunciated by James Hutton (1726–1797) and Charles Lyell (1797–1875), who argued that, during unlimited expanses of time, the Earth has undergone slow, ceaseless change by processes we can observe in operation. In their view, we cannot call on any powers that are not natural to the globe, admit of any action of which we do not know the principle, nor allege extraordinary events to explain a common appearance. A , originating from outside the Earth, and wreaking change instantaneously. Such a process violates every tenet of uniformitarianism. Largely for this reason, hypotheses of impact origin for craters on the Earth and the moon were vigorously opposed for the better part of the past century. Space-age research now has established beyond doubt the authenticity of impact as a geologic process, but an abundance of evidence exists that a wide chasm still persists between the views of impact specialists and those of terrestrial geologists. A full realization of the ramifications of impact processes may have been delayed by the advent of , which engulfed the geological community in the late 1960s. Revolutionary as it appeared at that time, plate tectonics, which is envisioned as involving gradual changes generated by forces internal to the globe, fully conforms with uniformitarian principles. In contrast, impact processes, which have recently been cited to account for cataclysmic events such as massive tsunami deposits, incinerating wildfires, and global extinctions, carry genuinely revolutionary implications that are fatal to the uniformitarian principle itself."