The tumuli of Scandinavia is of a great variety of designs, depending on the cultural traditions of the era in which they were constructed. The tumuli tombs may contain single graves, collective graves and both inhumation and cremation was practiced, again depending on the era, but also on geography. Many tumuli in Scandinavia shows a continuation of use from Stone Age to Viking Age. In the Viking Age (and perhaps in earlier times as well) burning the deceased, was believed to transfer the person to Valhalla by the consuming force of fire. Archaeological finds testifies that the cremation fire could reach temperatures of up to 1500 °C. The remains were often covered with cobblestones and then a layer of gravel and sand and finally a thin layer of turf or placed in urns. The tumuli were used for ancestral worshipping, an important practice in Norse culture and many places shows continuation of use for millennia.