Moraines are deposits of gravel-like soil, rocks and even boulders left by the movement of glaciers. Such deposits are generally conspicuous because they are out of place: boulders on flat plains, rocks and gravel that differ from surrounding types, suggesting a remote origin. Moraines frequently scoop the Earth as they move, leaving a wide groove-shaped pattern.

In the late 1700s, when geology was an emerging science, the prevailing belief was based on the Biblical myth that the Earth was only a few thousand years old. Evidence from moraines did much to discredit that view. As the first geologists began to investigate rock formations in England and other regions, they discovered unusual rocky debris and other indications that glaciers had once covered the land that was now bare. One of the first to realize that moraines were the product of ancient glacial movement was James Hutton, the "father" of geology and the author of the new concept of "deep" geological time. From his examination of rocky deposits and scraping patterns on cliffs, Hutton deduced that ancient glaciers must have moved over vast distances, picking up material in one region and depositing it thousands of kilometers away.

Hutton's (1795) ideas were treated as heresy in the Eighteenth Century, when moraines were interpreted as proof of the Biblical flood. It was not until the mid-nineteenth century that a majority of scientists accepted the idea of an ancient Earth and the evidence of a remote ice age.