Figure A-12. Photographs of core samples from Trenton and Black River formations in Consumer Power Company No. 219, 17-1S-8E.

1. 3882 ft--Dolowackestone with minor burrowing (Trenton).

2. 3907 ft--Skeletal wackestone from the upper Trenton. Fractures are lined with (1) ferroan dolomite and (2) nonferroan dolomite cement.

3. 3962 ft--Dolowackestone with solution-enhanced fractures which were later partially filled with dolomite (Trenton). Horizontal fractures do not cut across shale laminae.

4. 3974 ft--Extensively fractured skeletal wacke/packstone (Trenton). Fractures are lined with (1) moderately ferroan dolomite and (2) strongly ferroan dolomite cement.

5. 3996 ft--Vertical fractures filled with ferroan dolomite; partially filled vugs are lined with coarse dolomite (Trenton). Thin shaly micrite at bottom in a dolomitic wacke/packstone.

6. 4032 ft--Shaly crinoid wacke/packstone (Trenton). Both horizontal and vertical fractures are common. Fractures are lined with two stages of ferroan dolomite cement. The later stage cement is more ferroan.

7. 4060 ft--Dolomitic packstone with minor stylolite seams parallel to bedding and well-developed moldic/interparticle porosity (Trenton).

8. 4070 ft--Dolomitic packstone with interbed of shaly wackestone (Trenton). Solution enhanced moldic and intercrystalline porosity is common in the lower portion.

9. 4089 ft--Shaly wacke/packstone with excellent fracture porosity (10%), which is possibly solution enhanced (Trenton). Two stages of ferroan dolomite cement are locally followed by calcite cement in the fractures.

10. 4136 ft--Excellent moldic porosity in a dolopackstone (Trenton).

11. 4162 ft--Bryozoan packstone with good moldic and intercrystalline porosity (10%) (Trenton).

12. 4169 ft--Large bryozoan molds in upper portion of sample and excellent intercrystalline porosity in lower portion (Trenton).

13. 4201 ft--Shaly skeletal wacke/packstone (Trenton). Fragments of host dolomite (dark) have collapsed into large fracture and are cemented by coarse ferroan dolomite cement.

14. 4220 ft--Wavy bedded wacke/packstone (Trenton). Fracture direction appears to be controlled by texture: vertical in limy areas and horizontal in shaly areas.

15. 4246 ft--Irregular contact between wackestone below packstone (Trenton). White nodule left of center is anhydrite.

16. 4256 ft--Wavy to nodular bedding in shaly wackestone interval (Trenton). Large fossils in lower part are bryozoans and crinoids.

17. 4276 ft--Cherty, shaly wackestone (Trenton). Good intercrystalline porosity.

18. 4296 ft--Cross-bedded crinoid packstone (Black River). Sample is 100% dolomite.

19. 4322 ft--Burrowed dolomite wackestone interbedded with brachiopod- hash beds (Black River). White patch in lower left is an anhydrite nodule.