In the study of recent sediments the sample is usually small, and standard methods of study have limited application. This is particularly true in the study of the composition of very fine sand and silt-size materials. A simple and rapid method of study is as follows: 2 slides of each sample are prepared; one is a smear mount permanently set in "Permount" and the second in a gelatine medium. The latter is used for oil immersions. By examining these 2 slides under high-power binocular and petrographic microscopes, gross lithologies and textures may be determined. By means of a mechanical stage and a calibrated micrometer ocular, average grain sizes may be determined. Heavy minerals and light minerals mounted separately in the gelatine medium may be identified by liquid immersion. The oils are applied to the gelatine containing the mineral grains and covered with a cover glass. After examination, the cover glass is removed and the oil is washed away with acetone.