Final answer:
Charles Lyell and James Hutton theorized that Earth is much older than previously thought and that it has been shaped by consistent geological processes over time, known as uniformitarianism. Their research indicated that Earth's geological features were formed by the same processes that occur today, framing the Earth's age in billions rather than thousands of years.
Step-by-step explanation:
Charles Lyell and James Hutton both concluded that the Earth is extremely old and the processes that changed Earth in the past are the same in present day. Hutton introduced the concept that geological changes occur gradually through processes happening at a constant rate over time, which was later popularized by Lyell in the 19th century. Their work laid the foundation for the theory of uniformitarianism, suggesting that the slow-acting geological forces that shape our landscape indicate an older Earth, expanding the suspected age from thousands to billions of years.
Lyell's work had a profound influence on Charles Darwin, with the idea of Earth's greater age providing more time for gradual change, analogous to Darwin's theory of evolution. These fundamental geological principles became crucial for understanding Earth's history and the development of life. The method of absolute dating has since been used to put a precise age on Earth's geological timeline, finding the Earth to be approximately 4.54 billion years old.