Passive margins are characterized by thick accumulations of sediments. Sand dunes are accumulations of windblown sand piled up in mounds or ridges. Alluvial rivers with intense accumulations of sediment tend to this behavior. This is an indirect method for assessing the likelihood of ore deposits or hydrocarbon accumulations. Much of the city of Seattle proper received somewhat lesser snowfall accumulations. Rainfall accumulations exceeded in Nobeoka and in Saiki. Rainfall extended north to Guadeloupe were accumulations reached in Matouba. Methanogenesis is responsible for significant amounts of natural gas accumulations, the remainder being thermogenic. Massive accumulations of retrotransposable elements are scattered throughout the Y. Rainfall accumulations from the system peaked at in Nantucket, Massachusetts. The action of rivers and waves tends to pile up gravel in large accumulations. Coring accumulations of bat guano can be useful in determining past climate conditions. Most winters produce many snow falls during the season in light accumulations of around . Torrential rains battered Gujarat, with peak accumulations of in Bagasara, in Dhari, and in Variyav. The Oseberg field is one of a series of hydrocarbon accumulations within the Viking Graben.