The principle of uniformitarianism has long been used by geologists so that they can observe present processes to understand the geological past. Although the modern earth is different in many way from the Archean, with the atmospheric and oceanic chemistry being very different, there are still aspects which might be similar. The Lau basin, west of the northern part of the Tonga trench is believed to be a zone where potential continental crust is being created. Although the Lau basin is primarily oceanic crust, it is experiencing stress from multiple directions, so this results in rotations and small spreading ridges which propagate dynamically and experience intermittent spreading. Multiple ridges result in multiple microplates between the spreading centres. The whole basin is covered by high-resolution bathymetry and much of the plate-tectonic structure is evident from this data and earthquake moment tensor results, showing strong transform faulting. A large number of volcanoes are also present in the basin, with a variety of styles and spatial distributions. There is also gravity data and magnetic data from satellite and shipborne surveys. These remote-sensed data and sea-floor sampling can be used to create a geological map classified by lithology. The lithologies present in this map are similar to those seen in Archean terrane, with oceanic basalts being generated at spreading centres. The seismic surveys along a number of traverses have been undertaken, which allows the geology to be extrapolated to depth and structures to be inferred with greater confidence. There are indications of an upper and a lower crust and these varying in thickness along the profile. In the Archean crust, similar variability is seen in the thickness of the resistive and non-reflective granite greenstone terrane.