The Overton Down earthwork was constructed in 1960, the first of a series designed to study the changes which take place with time in a bank and ditch, and in selected materials buried within the bank. Full details of the construction of the earthwork are given by Jewell (1963); as this report will be referred to repeatedly, for simplicity it will in future be called the Basic Manual. The experiment was designed to be sectioned at intervals of 2, 4, 8, 16, 32, 64 and, perhaps, 128 years, though, in the early stages particularly, observations would be made at more frequent intervals. This paper deals with the results of the two- and four-year sections, together with such other observations as were made. Even at this date it has not been possible to complete the analytical work on all the buried objects; deficiencies will be made up as far as possible in future reports.