An apparatus is described for the quantitative study of sedimentation at different levels in lakes. A tray of 1 sq. meter area receives the descending material. This tray can be tightly closed before lifting it from the water, by means of a hydraulic device. Because of the large area and very low borders (5 cm.), the collecting error produced by narrow deep vessels is avoided. Even in oligotrophic lakes, enough material can be collected during one week for microchemical analysis.