Final answer:
The statement that uniformitarianism means present principles were also the same in the past is true, encapsulating the idea that the same geological processes observed today have always been active in Earth's history.
Step-by-step explanation:
The statement 'Uniformitarianism means present principles were also the same in the past' is True. Uniformitarianism is the principle that the same natural laws and processes that operate in the universe now have always operated in the universe in the past, and apply everywhere. This theory is summarized by the phrase 'The present is the key to the past' and is fundamental to our understanding of geology and Earth's history.
Scottish geologist Charles Lyell, a major proponent of uniformitarianism, argued that geological processes we observe today, such as erosion and sedimentation, have always occurred at similar rates throughout Earth's history. This concept was critical in establishing an understanding that the Earth is much older than the few thousand years that was previously believed and laid the groundwork for Charles Darwin's hypothesis of natural selection.