21. Its bedrock is Precambrian -era gray and black shale. 22. For that explains why we find no Precambrian proto-arthropod fossils. 23. The formation is predominantly Precambrian granite with outcroppings of quartz and schorl. 24. Mineralization occurs within the Laramide intrusive and in the surrounding Precambrian porphyry. 25. A thought just occurred to me on the subject of Precambrian rabbits. 26. The unit is of Cambrian age and rests unconformably on Precambrian rock. 27. It was deposited in a nearshore environment, unconformably overlying Precambrian basement. 28. The Precambrian Era dates from around 3850 to 542 million years ago. 29. They overlie Precambrian conglomerates and are overlain by the Calcaires de Laize. 30. Many of Canada's major ore deposits are associated with Precambrian volcanoes.
