Inman Valley is a town south of Adelaide. Selwyn’s Rock is a glaciated pavement in the Inman Valley about 60 km south of Adelaide in South Australia. It was first described by, and named for, Alfred Richard Cecil Selwyn, who was Victorian Government Geologist at the time. The glaciation occurred in the Permian period.
On the photograph grooves can be seen that run from lower right to upper left (this is the direction in which the glacier moved, toward the north-west). These were worn into the pavement by boulders dragged by the glacier as it scraped over the rock. The grooves themselves are thought to be 270 million years old and the rock pavement is reputed to be one of the largest of its type in the world.
Recently (in geological terms) the Inman River uncovered the pavement by washing away the overlying sediments. The rock is accessible to the public and is adjacent to the Glacier Rock Tea Rooms several kilometres south-east of the village of Inman on the Inman Valley Road.