The Transcontinental Arch refers to the islands of North America which extended from New Mexico to Minnesota and the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lak ...

region. These islands were present during the Sauk sequence, the earliest cratonic sequence. As a result of the Sauk sequence, epeiric seas covered most of North America, leaving only the

craton A craton (, , or ; from grc-gre, κράτος "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging an ...

of the Canadian Shield and the Transcontinental Arch islands exposed. The Transcontinental Arch, as originally understood, was at its peak during the Pennsylvanian, around 323 to 299 million years ago. However, the arch may have been present as early as the

late Proterozoic The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is prec ...

and experienced repeated rejuvenation throughout the

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

(521 to 252 million years ago).

References

Cambrian United States {{US-geology-stub