In 1838, his friend, Agassiz, suggested that he visited the Swiss glaciers. He visited the Swiss glaciers and communicated the results of his six-week investigation to the Geological Society of France. He was the first to point out certain important observations relating to glacial motion and structure. He also noted the more rapid flow of the center than of the sides, and the more rapid flow of the top than of the bottom of glaciers; described the laminated or ribboned structure of the glacial ice; and ascribed the movement of glaciers to a gradual molecular displacement rather than to a sliding of the ice mass as held by de Saussure. He also went on to collect important data concerning erratic boulders.