Stria

(Plural: striae) Also called striation Geology any of the parallel scratches or grooves on the surface of a rock caused by abrasion resulting from the passage of a glacier, motion on a fault surface, etc.

This photo (below) shows a bedrock surface exposed in a dolomite quarry in Wisconsin. The glacial drift has been removed. Continental glaciers polished and scratched (striated) the the dolomite. Photo by A.K. Hansel.

Glacial drift over bedrock photo

In the photo below, polished and striated bedrock is shown at the margin of a receding glacier in Iceland. The glacier is melting back toward the right of the photo. A closer view of the bedrock surface may be viewed by clicking on this photo. Photo by A.K. Hansel.

Glacial drift over bedrock photo

(Below) Striae closeup. Photo by A.K. Hansel

Glacial drift over bedrock photo