Complex sentence: The dunes are still moving 5 to 9 feet (1.5 to 3 m) per year and consist of quartz grains, minor amounts of feldspar, biotite, calcite, garnet and magnetite.
Split into simpler sentences: The dunes are still moving 5 to 9 feet (1.5 to 3 m) per year. The sand consist of quartz grains, with minor amounts of feldspar, biotite, calcite, garnet and magnetite.