Ideal for laboratory investigations by small groups of students in the study of stream types, stream development, erosion cycles, deltas, sedimentation and beach formations. Sturdy plastic tray is large enough for group study or individual investigation regarding rate of erosion as related to slope and stream volume. Includes heavy plastic tray, 48″ x 14″ x 3″, with drain, trough, 36″ x 2″ radius, support to raise tray or trough, siphon tube with clamp, 72″ x 1/4″. Sand not included. Grades 4-12.