Readers discuss cloud formation, Stonehenge and Earth’s frenemy Jupiter

Icy moves

Stonehenge’s central stone, known as the Altar Stone, may have had Scottish and not Welsh origins, researchers say. The finding suggests that Late Neolithic groups had long-distance connections, Bruce Bower reported in “Stonehenge’s roots extend to Scotland” (SN: 9/7/24 & 9/21/24, p. 10).

Reader Ralph Bradburd wondered if a glacier, not humans, could have at least partly transported the Altar Stone from Scotland to southern England, where Stonehenge is located.

That scenario is worth considering but is unlikely, says geoscientist Anthony Clarke of Curtin University in Perth, Australia. Ice sheet reconstructions show that glaciers moved northward from the Grampian Mountains in central Scotland toward the Orcadian Basin in the northeast, where the Altar Stone is thought to have come from, he says.