Along the south shore of Lake Superior is a sandstone once regarded as belonging to the Potsdam, but probably, in part , of the age of the Calciferous, in which we search in vain for any of those fossil remains so common in Minnesota. Whaterver its geological age, the Lake Superior sandstone is a formation of remarkable interest. This section across Lake Superior shows (a) water level. (b) trap outburst north of the lake, (c) trap outburst forming Isle Royale, (d) trap outburst forming Kewenaw Point, (e) Lake Superior sandstone and conglomerate. Eözoic and other rocks underlying the sandstone (f).