temps (durée) (1) roche (1) région (1) calcaire (1) karst (1) fer (1) eau courante (1) effet (1) dissolution (1) grotte (1) calcium (1) Dissolution (1) Ferric oxide (1) Wealth (1) Water (1) Walls (1) Units of measurement (1) Time (1) Sable (1) Quartz (1) Pebbles (1) Manganese (1) Limestone (1) Karst (1) Iron (1) Holes (1) Gravity (1) Fractions (1) Comprehension (1) Caves (1)