I regard this as a rather non-existent contradiction, more apparent than real. Chapter 10 is "the Table of the Nations", a listing of the descendents of Noah....born at various times ("Arpachshad" is born in 10:22, born two years after the Flood according to P in 11:10, and his great-grandson "Peleg" is born in 10:25, almost a hundred years later according to P). P in ch. 11 places Peleg half-way between Noah and Abram, and the obscure folk etymology in J in 10:25 ("in his days the earth was divided"), could possibly be an allusion to the J narrative in 11:1-9 (cf. the same use of the word "earth" in 11:1). Chapter 10 is simply giving a list of the descendents of Noah to show how the "70 nations" of the earth (cf. Deuteronomy 32:8-9) are geneologically descended from Noah's three sons. It has a different literary purpose than the first half of ch. 11, which tells a narrative of how the seperate nations of ch. 10 came into existence. Perhaps it would have read a little better for the redactor to have placed 11:1-9 before 10:1, but this would have destroyed the connection between ch. 10 and the narrative in 9:18-29 which concerns the sons of Noah and the grandson Canaan.