Thirty-seven surface sediment samples and 11 cores from the tidal portion of this 8-sq mi outwash fan are analyzed. Very poorly sorted muddy sediment and relatively well sorted sand overlie, for the most part, glacial outwash gravel. Mixing of modal size classes has produced complex patterns. The sand and mud are derived largely from Norris and Taku Glaciers; their nature indicates that valley glacier detritus may be fairly rapidly sorted by hydraulic action. No quartz and presence of feldspar in the clay fraction may indicate that physical properties control size to which they may be reduced by valley-glacier abrasion. Although the outwash is covered by saline water at high tide, fresh water flows out at low tide, showing that the sediment-water relationship is dynamic and that glacial meltwater is now flowing through the outwash.