PLEISTOCENE SERIES

Evolution of terminology

The classification and interpretation of the youngest stratigraphic sequences, variously known as Pleistocene, Holocene, and Quaternary, have been, and still are, a matter of debate. During the first two decades of the nineteenth century, many of the sequences were attributed to the biblical flood (the “Diluvial” theory). This theory could account for unconsolidated sediments that rested unconformably on “Tertiary” rocks and capped hills, and that commonly contained exotic boulders and the remains of animals, many still extant. This origin for the “Diluvium” was accepted by most eminent geologists of the time, including Buckland and Sedgwick.

Floating ice had frequently been seen transporting exotic materials, providing an explanation for the transport of the boulders, and reinforcing the Diluvial theory. This explanation lead to adoption of the term “drift” to characterize the sediments. However, geologists working in the Alps and northern Europe had been struck by the extraordinary similarity of the “drift” deposits and their associated landforms to those being formed by modern mountain glaciers.