Complex sentence: As a glacier moves downhill through a valley, the shape of the V-shaped valley is transformed into a U-shaped valley through the glacial erosion processes of plucking and abrasion.
Split into simpler sentences: As a glacier moves downhill through a valley, the shape of the valley is transformed. A V-shaped valley is transformed into a U-shaped valley through the glacial erosion processes of plucking and abrasion.