The New Beginings of January Precambrian Era:PRECAMBRIAN GEOLOGY, Establishing Precambrian boundaries

There is no record of tectonic activity of any sort at the time corresponding to the Archean-Proterozoic boundary—about 2.5 billion years ago. This probably means that a supercontinent had been created by the amalgamation of innumerable smaller continental blocks and island arcs. Accordingly, this was a period of tectonic stability that may have been comparable to the Permian-Triassic when the supercontinent of Pangea existed. The main geologic events would have been the intrusion of basic dikes and the formation of sedimentary basins such as the Huronian on the U.S.-Canadian border, into which large volumes of clastic sediment (that is, sediment of predominantly clay, silt, and sand sizes) were deposited. Such sediments would have been derived by erosion of high plateaus and mountains that are characteristic of a large continental mass.