<P> Laurentia is an ancient craton which forms the geologic core of North America ; it formed between 1.5 and 1.0 billion years ago during the Proterozoic eon . The Canadian Shield is the largest exposure of this craton . From the Late Paleozoic to Early Mesozoic eras , North America was joined with the other modern - day continents as part of the supercontinent Pangaea , with Eurasia to its east . One of the results of the formation of Pangaea was the Appalachian Mountains , which formed some 480 million years ago , making it among the oldest mountain ranges in the world . When Pangaea began to rift around 200 million years ago , North America became part of Laurasia , before it separated from Eurasia as its own continent during the mid-Cretaceous period . The Rockies and other western mountain ranges began forming around this time from a period of mountain building called the Laramide orogeny , between 80 and 55 million years ago . The formation of the Isthmus of Panama that connected the continent to South America arguably occurred approximately 12 to 15 million years ago , and the Great Lakes ( as well as many other northern freshwater lakes and rivers ) were carved by receding glaciers about 10,000 years ago . </P>
<P> Laurentia is an ancient craton which forms the geologic core of North America ; it formed between 1.5 and 1.0 billion years ago during the Proterozoic eon . The Canadian Shield is the largest exposure of this craton . From the Late Paleozoic to Early Mesozoic eras , North America was joined with the other modern - day continents as part of the supercontinent Pangaea , with Eurasia to its east . One of the results of the formation of Pangaea was the Appalachian Mountains , which formed some 480 million years ago , making it among the oldest mountain ranges in the world . When Pangaea began to rift around 200 million years ago , North America became part of Laurasia , before it separated from Eurasia as its own continent during the mid-Cretaceous period . The Rockies and other western mountain ranges began forming around this time from a period of mountain building called the Laramide orogeny , between 80 and 55 million years ago . The formation of the Isthmus of Panama that connected the continent to South America arguably occurred approximately 12 to 15 million years ago , and the Great Lakes ( as well as many other northern freshwater lakes and rivers ) were carved by receding glaciers about 10,000 years ago . </P>
when did north america arrive at the location it is in today
when did north america arrive at the location it is in today
mid-Cretaceous period
mid-Cretaceous period