Nice find Jacob. Great resources available to work from in making your own maps it looks like. Enjoy! And, if you want to, let us know down the road what you find.

As to this substrate map, you are right it is old. Development around the area will have changed things tremendously. This is now like archeology -what you see in this map is what's beneath a lot of new silt and organic material. Vegetation will be much denser now and will add to the organic layers. Harder substrate will be harder to find now I would guess. Again vegetation will be key.

http://www.dnr.state.mi.us/SPATIALDATALIBRARY/PDF_MAPS/INLAND_LAKE_MAPS/MACOMB/STONY_CREEK_IMPOUNDMENT.PDF

UPDATE NEW MAP FOUND a bit old but it gives a general idea of the bottom composition.

Good find. Clay is finely ground rock, gravel is the next level of small rocks, both are important bottom materials because neither support weed growth without added mix of soil and organic material. Good places to check out to determine if a break line still exists.

You have done about you can; learned about depth changes, deep water break lines and soil changes. Now study weed types; the less dense types like coon tail and cabbage that allow the bass to tunnel through passages or cruise along the weed edges and open pockets are better then junk weeds that form a tangled mess.

Good luck and lets know how things develop for you.

WRB