Like conglomerates, breccias are siliciclastic rocks comprised of a framework of clasts (>2 mm)within a finer-grained matrix. Conglomerates and breccias are distinguished apart based on the angularity and roundness of their clasts. Breccia clasts are angular with much sharper edges, and conglomerates are generally round. This sample is classified as an oligomictic orthobreccia due to the grain-supported matrix of angular, pebble-sized (4-64 mm in diameter) chert clasts within a very fine-grained mud infill. The red colour of the matrix may be due to ferric oxides.