This data set is the result of a study of volcanic ash and rock fragment (tephra) layers in exposed blue ice areas on Mt. DeWitt, Antarctica (77.12 deg S, 159.51 deg E). Tephra samples were collected between 15 November 1996 and 15 January 1997. Data include the following information for each sample site: a general description, electron microprobe analysis, GPS location, neutron activation analysis, and a visual description of the petrography. Data are provided as an Excel 97 data file, (this file is also divided into various text files) and TIF images. Data are available via ftp. Antarctic ice sheets preserve a record of the volcanic ash layers and chemical aerosol signatures of local and distant volcanic eruptions. Correlation of individual tephra layers, or sets of layers, in blue ice areas will allow a better understanding of the geometry of ice flow in these areas. Tephra layers in deep ice cores can also provide unique time-stratigraphic markers in cores that are difficult to date.