Jasper conglomerate

Jasper conglomerates are a distinct type of glacial erratic collected mostly from glacial drift. The conglomerates were derived from the North American region of the Canadian Shield that is present on St. Joseph Island and north and northwest of the Bruce Mines of northern Ontario approximately a 65 km east of Sault Ste. Marie. This rock is derived from the Precambrian Lorrain Formation, which contains rocks associated with Precambrian (2200-2400 Mya) glaciation and the jasper conglomerates are attributed to sand and pebbles derived by erosion from older rocks and redoposited as gravity flows in water. The red pebbles or cobbles in the conglomerate are fragments of jasper or banded iron formation. Later these materials were lithified to form conglomerates and transformed by heat and pressure to form quartzite conglomerates. The early British settlers in the Bruce Mines, called the jasper conglomerate “puddingstone”, because it looked like boiled suet pudding with cherries. The main use of the jasper conglomerate is for decorative purposes.

See also

• Hertfordshire puddingstone
• Roxbury puddingstone
• Ornamental stone