Modern glaciers and ice sheets cover approximately 10% of the world's land area. Of this, most glacier ice is found in Antarctica and Greenland with all other areas accounting for only about 5% of the total. During the Ice Age (Pleistocene Epoch) of the last one million years, glaciers and ice sheets expanded dramatically and repeatedly over large portions of northern Eurasian and North American lowlands and in mountains and high plateaus around the world. At times, the volume of glacier ice during the Pleistocene was at least triple that of today (Hughes et al., 1981). Global sea level declined by at least 120 m, which allowed ice sheets to spread over broad continental shelves, particularly north of Eurasia (Svendsen et al., 1999; Polyak et al., 2000).

Geomorphology is the study of the Earth's surficial landforms both on land and on the seafloor. This study is both descriptive and quantitative; it deals with morphology, processes, and origins of landforms. Glacier ice is a powerful agent that created many distinctive landforms that are well preserved nowadays in regions of former ice expansion. Glaciers modify the landscape in three fundamental ways by erosion, deposition, or deformation (Fig. 12-1). A given site may be subjected to each or all of these processes during the advance and retreat of a glacier, and repeated glaciation may overprint newer landforms on older ones. In addition, glacial meltwater is also an effective geomorphic agent that may erode or deposit conspicuous landforms in connection with glaciation. The results are complex landform assemblages that represent multiple glaciations during the Pleistocene.

Aerial photography has long been utilized to illustrate, describe, interpret, and map the diverse types of landforms created by glaciation (e.g. Gravenor et al., 1960). Traditionally this approach is based on medium-scale, panchromatic, vertical airphotos taken from heights of several thousand meters (Fig. 12-2). In recent years, satellite imagery has been utilized increasingly for glacial geomorphology (Williams, 1986). Low-height, oblique airphotos also have proven effective for recognizing and displaying various types of landforms (e.g. Dickenson, 2009), including distinctive glacial landforms such as eskers and drumlins (Prest, 1983). The advantage of oblique views is the ability to visualize the three-dimensional expression of individual landforms within the surrounding terrain (Fig. 12-3).

The following small-format aerial photography (SFAP) was acquired with kites and a small helium blimp at formerly glaciated sites across the United States and several countries in northern Europe. All represent landforms created during the last major glaciation in the late Pleistocene, some 10,000 to 25,000 years ago. Because of their young age, the landforms are fresh and well expressed in the landscape. They are grouped according to the main geomorphic process involved in their formation.

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