 Many of the dunes reach an altitude of and in a few places exceed .The highest are confined to a belt scarcely a mile in width, but lower ones appear for several miles back of these, in the sandy area between Holland and Muskegon and in that west from Michigan City.Dunes are lacking chiefly at points where the lake is encroaching on morainic ridges, as on those of the Lake Border morainic system in the southern end of the basin.