How can catastrophic events be used to support Hutton's geologic principle of 'Uniformitarianism'?
First, let's define uniformitarianism. It is the postulation that the geologic principles that operated in the past are the same as those that are operating today. The opposite view is supposed to be catastrophism, the postulation that Earth's geologic features are a result of sudden and catastrophic processes that are not currently in action today. Catastrophic events, however, are perfectly compatible with uniformitarianism, as events such as flooding can occur due to normal processes such as headward erosion toward large bodies of water, and climatic caused ice melting during periods of glaciations. Large meteor impacts have been recorded in the past, and so have eruptions of supervolcanoes. These catastrophic events are going to occur again and are considered a part of, just not a highly predictable part of, the geologic cycle.