Conglomerate, sedimentary rock, from Batchawana Bay, Ontario. Keweenawan, late Cambrian or early Paleozoic age. These conglomerates are rich in granite boulders. The boulders are cemented together with red sandstone. Rocks of this age are the source of rich native copper deposits on the Keweenaw Peninsula of Northern Michigan. These deposits produced more wealth than the California Gold Rush. A similar small deposit was found at Mamainse Point. Keweenawan rocks consist of interbedded conglomerates and lava flows. The gas-bubble holes formed at the top of lava flows have filled with chlorite (green mineral) seen in these lava specimens in the geological garden. Other minerals filling the holes include calcite and epidote.