Detritus is the collection of dead stems of Spartina and other things that float. This combination of materials floats up in the marsh during high tides, and winds often drive it ashore, where it piles up in a thick mat. As the mats decompose, they are food to many organisms, and they provide a shelter from the hot, drying sun. Sometimes the detrital mats break loose from the shore, or the winds blow the mats into the creeks. On the open beach, detritus piles up at the wrack line, just above the high tide mark.