Question

The underlying theory which is foundational to current geological thinking is:

uniformitarianism
neptunism
plutonism
catastrophism

Answer 1

Uniformitarianism is defined in the authoritative Glossary of Geology as "the fundamental principle or doctrine that geologic processes and natural laws now operating to modify the Earth's crust have acted in the same regular manner and with essentially the same intensity throughout geologic time, and that past geologic events can be explained by phenomena and forces observable today