The oldest known source which mentions the name "Iceland" is an 11th-century rune carving from Gotland, while the oldest archeological finds indicating settlement date back to the 9th century. There is a possible early mention of Iceland in the book "De mensura orbis terrae" by the Irish monk Dicuil, dating to 825. Dicuil claimed to have met some monks who had lived on the island of Thule. They said that darkness reigned during winter but that the summers were bright enough to pick lice from one's clothing, but the veracity of this source may be questioned. Additionally, Iceland is only about 450 kilometres from the Faroes, which had been visited by Irish monks in the 6th century, and settled by the Norse around 650.