The systematic arrangement of Grenville and Appalachian orogens around the older core of the continent inspired Wilson's (1966) query regarding the Atlantic closing and reopening, and lead to the concept of the Wilson Cycle (Wilson et al., 2019) that envisages repeating assembly and breakup of continents. Alignment of along strike offsets in the Grenville and Appalachian tectonic units of eastern North America with locations of the most recent continental breakup that produced the modern Atlantic was used by Thomas (2006) to articulate a concept of tectonic inheritance. It posits that episodes of continental assembly

Cratons are large domains of the continental crust which have experienced little internal deformation and have maintained long-term stability since their formation during the Archean epoch. This stability makes cratons the only places on Earth that retain the geological record from the first half of Earth's existence. Layering of seismic properties within the cratonic lithosphere is a major form of such preserved record. It was reported in Superior, Slave and Wyoming cratons in North America, the Western Australian craton, and the Kalahari craton in

Cratons are large domains of continental crust, which have experienced little internal deformation and have maintained long-term stability since their formation during the Archean epoch. Most cratons are composed of numerous distinct terranes formed relatively early in Earth's history and are assembled by processes that continue being debated (

Eastern North America records a tectonic history of over 3 Ga in duration. Much of this record is preserved within the lithosphere and may be unraveled by detailed studies of its interior structure. Past episodes of tectonic activity likely left their imprints in the form of anisotropy‐forming rock fabric presently preserved in the lithosphere of the continent. We perform shear wave splitting measurements using observations of core‐refracted waves collected from a ~1,300‐km‐long array extending from James Bay in Quebec to the Fundy basin in Maine, with lateral spacing of 10–100 km between instruments. Close spacing of instruments helps us associate anisotropic properties with geological boundaries. We find that the fast polarizations concentrate between N60°E and N90°E with an average of N80°E and change systematically with backazimuth. In addition, we observe a lateral increase in delay time from 0.56 ±0.25 s at the NW end of the array to 0.90 ± 0.41 s at the SE end. The location of lateral change in delay time does not match geological boundaries on the surface but seems to match the geophysical boundary at depth of 160 km. We interpret this boundary in splitting values to be the edge of cratonic lithosphere at depth. Our observations suggest that the anisotropic structure beneath our study area is complex and possibly both multilayered and laterally variable.