Erratics – Rocks which have been transported and deposited by a glacier some distance from their source region
Her attic (erratics) was full of rocks and she threw them into a skip to be transported and deposited some distance away.
The erratics or boulders don't match the geology of the surrounding landscape.
Erratics were originally produced by glacial erosion and, in some cases, avalanches creating rock falls. They were then transported by the glacier, sometimes up to hundreds of miles, before being deposited. Some were carried on ice "rafts" that originated from glacial ice before sinking to the bottom of lakes or the sea as the rafts melted.