The shape of a river stone can provide clues about its journey. Flowing wa carries lo pieces wh repeated imp gradually rem sharp cor from th surfaces a produce smoo shapes ov long periods. A fragment that has recently broken from a rock may therefore look different from one transported for a long distance. Shape is not a perfect record, however. Different rocks resist wear differently, and a stone may spend years resting in one place before moving again. Interpreting its history requires considering the material as well as its appearance.

Type only the missing letters. Each box is one letter, and the number of boxes matches the letters that are missing.