[en] Significant amounts of fallout ¹³⁷Cs from nuclear weapons tests were introduced to the landscape during the 1950s and 1960s. Once ¹³⁷Cs reaches the soil surface it is strongly and quickly adsorbed by clay particles, and is essentially nonexchangeable in most environments. Thus, ¹³⁷Cs becomes and effective tracer of the movement of soil particles across the landscape. Over the past 30 years, researchers have shown that ¹³⁷Cs can be used to study soil movement. Early work used empirical relationships between soil loss and ¹³⁷Cs loss to estimate erosion. This was followed by the development of proportional and theoretical models to relate ¹³⁷Cs movement and soil redistribution. Most of the problems related to the ¹³⁷Cs technique are the same as those encountered with other techniques (i.e., sampling, measurement). The ¹³⁷Cs technique can make actual measurements of soil loss and redeposition in fields, fostering the formulation of better plans to conserve the quality of the landscape. This paper reviews the development of the ¹³⁷Cs technique to show how it can be used to understand erosion and soil movement on the landscape. (author)