Green in general is a color indicator, I use for various other targets mostly archaeological (old ruins or foundations but especially those non-metallic objects such as Indian flints, glass, pottery, carved stone with treasure signs).
Red X for deep coins/treasure or artifacts of value (doesn't have to be a cache).
Red circle is to mark areas, of loose or surface coins/treasure and artifacts of value, down to 1-2 feet deep.
Dowsing revealed an attraction to silver in the areas of the blue circles. Bold circle is a pinpoint area and thin circle is a wide area of loose coins. Check the foundation area of the bldg in the blue rectangle for coins/sm coin caches in the walls,and at the ground level and below ground.Thanks for posting your picture.Jon