Hot, exposed heathland dominated by low shrubs that nearly cover the ground. Sand barrens include stretches of windblown sand, dunes and loess (silt) deposits that were created from deposits left by receding glaciers during the last Ice Age. Low shrub species, some of which form carpets or cushions of growth, develop on the nutrient-poor, sandy, dry acidic soils. Few tall trees or shrub species grow in sand barrens, creating a very exposed ecosystem with little shade. What trees do grow in a sand barren are stunted due to the harsh climate.