Little is known about the paleogeography, or ancient geography, of early Earth. The earliest continental crust is found in cratons, which are the ancient cores on continents. They also contain all three types of rocks that each tells their own story about the Precambrian era.
Shields are where cratons crop out at the surface. Many Precambrian shields are about 570 million years old. Cratons covered by younger rocks are called platforms. When these platforms undergo erosion, the Precambrian craton is exposed.
Early crustal plates were small due to faster mantle convection and stronger plate tectonics processes. These processes also created more subduction zones.
Plate tectonics: Smaller microcontinents collided to create bigger supercontinents, which resulted in the formation of massive mountain ranges. An active period of convergence was between 1.5 million and 1.0 million years ago. Cratons collided with microcontinents and oceanic island arcs to form Laurentia, which is part of the supercontinent Rodinia. Around 750 million years ago, oceans began forming in between continents as the result of Rodinia’s disintegration.