Abstract

A common lithic mterial found in archaeological deposits of west-central Manitoba is Swan River chert. The distribution of this variegated chert extends across Saskatchewan as far West as east-central Alberta. No bedrock outcrop is known as yet, but considerable quantities of this material are present as cobbles in the glacial tills of the region. The great variation in the colour and texture of Swan River chert is discontinuous, so that about 20 to 35 distinct varieties can be macroscopically discerned. Several questions arise at this juncture. Do the 25 or so varieties represent different cherts with perhaps differences in flaking characteristics? If all varieties consist of only one chert type, a standardized description must be provided so that Swan River chert found within the region, more distantly, or in trading contexts can be readily identified. A standardized description would facilitate the determination of the full extent of its use through time and space. Preliminary analysis of some 30 thin sections of Swan River chert indicates no congruence between macroscopic and microscopic appearance. Aside from minor variations, all but two of the Swan River chert varieties exhibited the same three crystal habits: (1) medium-grained chalcedonic spherulites with flamboyant structure; (2) medium to large-grained euhedral granoblastic quartz grains; (3) fine silt-sized anhedral quartz crystal aggregates. Varieties not exhibiting the tri-modal crystal habit are not considered to be Swan River chert. Features pertaining to the genesis of this material remain contradictory.