Fig. 10--Photomicrographs of Trenton textures.

1. Bryozoan and crinoid-rich packstone. Dolomite (brown patches) replacing unidentified fossil fragments, including bryozoan zooecia. PPL. Davis Wooden No. 4, 3883 ft.

2. Stained thin-section of a dolomitic packstone. Calcite is red and dolomite is light to dark blue. Many of the skeletal fragments are silicified. Torosian Nerreter No. 1, 4487 ft.

3. Shaly, dolomitic zone at the base of the Trenton. This zone corresponds to gamma-ray deflection separating the Trenton and Black River. PPL. Carter Lauber No. 12, 5706 ft.

4. Zoned baroque dolomite filling a large fracture in stained thin-section; late stage dolomite is ferroan, and a later-stage calcite (pink) is at the top. PPL. Torosian Nerreter No. 1, 4348 ft.

5,6. Coarse baroque (5) dolomite partially coated with calcite (pink). UV fluorescent photomicrograph (6) of the same view; pinpoint clusters in the outer rim of the dolomite are liquid hydrocarbon inclusions. They occur in the middle-stage dolomite, not in the earlier dolomite growth or the later calcite. 5, PPL. Torosian Nerreter No. 1, 4380 ft.