As I alluded, uniformitarianism is a somewhat anachronistic term, because it hails from a founding era of geological debate for which that dichotomy no longer frames discussion. By now these aspects of geological discourse have long been subsumed into the tectonic model and much more detailed understanding of the epochs of earth history. The real point is this, that whether one is dealing with gradual processes or a cataclysmic episode such as the Chicxulub impact that ended the era of the dinosaurs, the underlying principles are continuous and uniform .
The build up of chalk formations over millions of years is entirely consistent with applicable and observed principles. The explosive impact of the asteroid is also entirely consistent with physical principles of energy conservation, and accords with unmistakable evidence of cratering, global dispersal of well defined chemical and impact signatures, and a spectacularly abrupt and pervasive discontinuity in the fossil record over the entire planet.
Even gradual processes are characterized by change over eons. The changes in the Earth’s atmosphere and ocean is recorded in the mineralization cycle. So, between catastrophic change and steady change over geological time, uniformitarianism is simply a mischaracterization of what scientists have recognized now for many decades, and that is change is both constant and punctuated.
What are uniform, however, are the underlying principles which serve to unify and explain disparate phenomena. The field theories which govern subatomic physics from weapons to astrophysics to radiometric dating are based on observational science. Half lives are not independent variables, they are dependent on these more fundamental principles.
For another instance, the plate tectonic model unifies observations, both current and recorded in geology, of the earthquake and volcanic activity of the ring of fire, including your neighborhood. It explains the pattern of magnetic reversals found in the spreading fissures of the oceanic trenches. It explains how the continents are shaped to fit together, and why the same formations are found as severed halves. It explains the rising majesty of the Himalayas, and the ground down Canadian Shield. It explains why some rock is young with crystals rich in parent species, and other rock is old and full of daughter isotopes. As @Michael_Callen pointed out above, it explains the pattern of the Hawaiian chain through to Alaska, as well as the Galapagos. It is consistent with what we expect to be driven from the heat balance of the Earth’s core. And plate tectonics is observed; movement is well within the sensitivity of our instrumentation.
So we have basic principles derived from observational science with tremendous explanatory power. YEC rejects the application of these basic principles, not because of any failure in the observation, but because of the theological implication. There is no scientific grounds for such dismissal. It is observational, experimental, and operational science that has yielded these principles. So I do not give credence to the contention that YEC accepts observational science.
