Carrock
From Tolkien Gateway
The Carrock was a stony eyot in the upper reaches of the River Anduin, to the north of the Old Ford.
In T.A. 2941, Thorin and Company were placed there by the Eagles. Gandalf stated then that the steps from the base of the rock to the flat top were made by Beorn and that "Carrock" is Beorn's name for it.
Radagast the Brown's home, Rhosgobel, was near Carrock.
Etymology
This is somewhat of a linguistical joke on Tolkien's part, since car in Celtic means "rock" (English carg).
Carrock Fell is a peak in Cumberland.