Final answer:
James Hutton introduced the theory of gradual geological change, but it was Charles Lyell who popularized and significantly developed the concept of stratigraphy with his ideas of uniformitarianism in the 19th century.
Step-by-step explanation:
The concept of stratigraphy was developed by two pivotal figures in the history of geology: James Hutton and Charles Lyell. James Hutton, a Scottish geologist, laid the groundwork by proposing that geological change occurred gradually through small changes in processes operating over long periods of time. This theory contrasted with the predominant view at the time, which favored catastrophic events as the primary drivers of geological change. However, it was Charles Lyell who popularized Hutton's ideas in the nineteenth century. Lyell's work, particularly his publication Principles of Geology, was influential in advancing the concept of uniformitarianism—the idea 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 in the universe.
Lyell's perspectives were especially significant in the development of evolutionary thought by providing a framework for understanding Earth's extensive geological past. Though both Hutton and Lyell contributed to the concept, the credit for the development of stratigraphy often goes to Lyell due to his role in popularizing and elaborating the theory.