While the idea that Earth had experienced periods of cold, ice-covered epochs existed long before, the first scientific articulation of the theory of glacial ages is generally attributed to Louis Agassiz in the 1830s.

Here's a breakdown:

* Before Agassiz: People had observed glacial features like moraines and erratic boulders, but attributed them to biblical floods or other unknown events.

* Agassiz's Contributions:

* In the 1830s, Agassiz, a Swiss geologist, began studying glaciers in the Alps.

* He recognized the distinctive features left by glaciers and proposed that vast ice sheets had once covered much of Europe and North America.

* He presented his theory in a series of lectures and publications, sparking debate and eventually gaining widespread acceptance.

However, it's important to note:

* Prior Ideas: There were earlier theories of glacial periods, like those by Ignaz Venetz and Jean de Charpentier, who influenced Agassiz.

* Evolution of the Theory: The concept of glacial ages has evolved significantly since Agassiz's time. Scientists have developed a more detailed understanding of the causes, timing, and impact of glacial cycles.

So, while Agassiz is recognized as the first to formally present a scientific theory of glacial ages, the idea was not entirely novel. His work laid the foundation for further research and a deeper understanding of Earth's climatic history.