15-Tillite

Ancient conglomerate interpreted as glacial till (unsorted boulders, pebbles, and clay) not related to the more modern Pleistocene glaciations. Rock contains partly rounded pebbles of granite (pink) and basalt (dark) rock, in finer rock matrix. Original till was deposited in Canada by ancient (Precambrian) glaciers, then buried lithified to form tillite, then metamorphosed to metatillite about 2 billion years ago. Boulder found in Pleistocene glacial outwash in France Stone quarry. (Compare with no. 16, no. 17, and no. 18.)