The presence of an ice core or ice cement has arrested soil formation on hummocky drift behind Trilogy, Loop, and C end moraines in eastern Wright Valley. Soils on the Trilogy and Loop hummocks contain fewer salts and are coarser in texture than soils on the associated end moraines. Lack of soil development on hummocks is due to frost heaving and sorting, and while soils on hummocks behind the Loop end moraine may be as old asc. 135 000 y. b.p., they have properties more closely resembling the 18 000-year-old Trilogy soils. Data suggest that soil chronosequences may be invalid where component soils have been disturbed by frost action, and that soils on comparable sites must be used for comparative weathering studies.