From the Super Mario Wiki
Sand Spouts (or Sand Geysers) are pillars of sand that rise up out of bottomless pits. They can temporarily help the player cross gaps and reach elevated areas. If Mario jumps into one, he is carried up to the top of the geyser by its force. They appear in New Super Mario Bros. Wii and New Super Mario Bros. U, in World 2-1 and World 2-5, and Spike's Spouting Sands and Blooming Lakitus respectively, as one of the main elements of the levels. They also appear in the World 2 map, between World 2-5 and the Spiny Enemy Course. Additionally, Sand Spouts also appear in the World Coin-4 in Coin Battle mode. They have the same functions of Water Spouts, that appear in New Super Mario Bros. U.