The studied area is located in Northwestern Québec between 48° and 49° 30' N, and 77° 15' and 79° W. Eskers in this area have dimensions in the order of 100 km in lenght and 50 m in height. Between the eskers lies a clay plain formed by sedimentation in the bottom of glacial lake Barlow-Ojibway. Some features of the bedrock structure influenced the deposition of the eskers in two ways : by forming obstacles in the path of the eskers, and by orientating them along major fault lines. Morphological modifications of eskers by wave action show three evolutionnary steps in the life of lake Barlow-Ojibway : a maximum level at 366 m (1200 ft), a gradual lowering from 366 m to 330 m (1100 ft) and a last level between 330 and 320 m (1050 ft). The withdrawing of lacustrine waters was followed by a tardiglacial aeolian activity on beach and glacio-fluvial sands. The eskers between Bell and Harricana rivers were divided in six morphological types with the help of factor analysis, and five of these types were associated with respective modes of formation. It appeared in this study that the most important esker of the area, called the « Matagami esker », is in fact a very large interlobate deposit.