Bancroft tells his students that above Montreal there once lay from 1/2 to 1 mile of strata now gone. Atica 1000 feet thick. Dr. Banno has typified back grounds the youngest about Montreal. North east of Quebec around the shores of the lakes his most Diagonan material, Bancroft thinks this is from Silurian in place, Look of the paleogeography, There is a Trenton outline on the shield north of Montreal. See Bancroft.