Here in Alys Beach, on the coast of Florida’s panhandle, the sun is so intense that even on a mid-September day my husband, David, and I wait until early evening before crossing over the pristine dunes with our infant daughter, Ailigh. The dusk light is a watercolor play of pinks and indigos washing over a reflective canvas of fine quartz particles, ground away from the Appalachian Mountains during the Ice Age and carried by the Apalachicola River into the Gulf.