Albert Barnes Commentary Joshua 7:26

"And they raised over him a great heap of stones, unto this day; and Jehovah turned from the fierceness of his anger. Wherefore the name of that place was called, The valley of Achor, unto this day." — Joshua 7:26 (ASV)

A great heap of stones - As a memorial of Achan’s sin and its punishment. (2 Samuel 18:17).

The valley of Achor - Compare the marginal references. This valley formed part of the northern border of Judah (Joshua 15:7); and must therefore have lain among the ridges which cross the plain to the south of Jericho. But its exact site is uncertain. (Conder identifies it with Wady Kelt.)