In the red clay region of Douglas County, Wisconsin, three types of stratigraphic succe. s1lon are obsorvod from borehole dato: red clay 8 m (25 ft) thick over older red clay, red clay over brown or g111y clay, and rod clay over brown sand. The mean contents with standard deviation of sand (> 44 µm), silt (44 to 2 µml, coarse clay (2 10 0.2 µm), and fi no clay (< 0.2 µm) in red clay from 28 borehole samples are 4: I: 4, 24: I: 12, 42±7, and 30: I: 6. Smectite clay is dominant in the flno clay fraction; lllito and chlorite are dominont in the coarse clays; and quartz, feldspars, and carbonates are dominant in tho slit and send fractions. Pan iclesite distribution and mineral contents correlate with the At: torberg limit values. Tho equations Liquid limit= 10.0+ 0.78 (%< 2 µm clay) and Plnnicity index=-0.1+ 0.51 (%< 2 µm clay) have correlation coefficients of 0.76 and 0.84, respeetlvely, for this body of data. Tho dominont failure mode in tho Little Balsam Crook drainage south of'Suporior and in other timilar locales involves drying and cracking of a surficial layer of clay that then slldes as a decollement sheet over the underlying clay. This failure may have been promoted by recent cultural practice in the area.

Along the shore of Lake Superior from Michigan to the Minnesota border, is an extensive area of redbrown clay-rich sediments that have locally been dubbed the• red clay.• The focus of this paper is on the characteristics of this material in Douglas County, Wisconsin. As the observed properties of the red clay are roughly similar throughout Douglas County, it is probable that the characteristics described here will be found throughout the red clay region. The red clay underlies the gently sloping Superior plain that, in Douglas County, ranges from about 190 m (625 ft) above mean sea level along the lake to about 335 m (l, 100 ft) along the South Range, a sand-covered highland with a lava bedrock core. The South Range is the south boundary of the red clay region (see Figure l). The red clay is