Climatic variations lasting a few days can produce variations in the coarseness of the grain size within the summer phase of glacial varve couplets. Studies of size distribution made with a Quantimet 720 make it possible to resolve these variations in grain size. This allows correlations between varves in the same basin of deposition on the basis of internal features as well as on sequences of varve thicknesses. Similarly improved correlations between basins will be possible. The internal structures of varves are now a potential factor in determining climatic cycles or periods of less than one year.