The red circle areas should be the better places to check metal detecting. Here is from my file, general definition for these types of marked spots.
Red circle is to mark areas, of loose or surface coins/treasure and artifacts of value, down to 1-2 feet deep.
Red line box for very deep coins/treasure or artifacts of value.
Green line boxes in general for various other targets, mostly archaeological such as old ruins or foundations but especially non-metallic objects like flint arrowheads, bottles, pottery, and carved stone markers.