232 GEOLOGY OF OHIO. 



responds, in general, with that in the island of Mackinac, although it 

 shows at the latter place a greater thickness, and is not separated by a 

 belt of regularly laminated beds into two portions. Yet this tendency to 

 the rough and brecciated condition has been seen even in the very bottom 

 of the formation. In the quarry of Messrs. Newman and Ford, at Genoa, 

 there are irregular masses of porous and brecciated rock, which, by ce- 

 menting and breaking up the bedding, give the formation a massive 

 structure. In the bed of the Portage, in section 9 (Harris), there are sin- 

 gular, dome-shaped masses of rough and vesicular, or brecciated, Water- 

 lime, standing out six to eighteen inches above the glaciated surface, on 

 which the even beds. (phase No. 3), which are thin, seem to have been 

 deposited unconformably, or are arranged concentrically about the mass. 

 The following downward section covers all the quarries at Genoa : 



Section at Genoa. 



No. 1. Thin beds, 1 to 3 inches, drab 1 foot. 



No. 2. Brecciated and carious, with cavities and fossils 6 to 12 feet. 



No. 3. Green shale, weathering blue 1 foot. 



No. 4. Niagara (Guelph), beds 3 to 6 inches 16 feet. 



The quarries of Messrs. Newman and Ford, and of Wyman and Gregg, at 

 Genoa, are in the base of the Waterlime. Other quarries at the same 

 place are situated in the top of the Niagara. 



The Waterlime underlies a strip about two miles wide north and south 

 along the western end of the county, and a large area in the center. It 

 also crosses " the Peninsula " through the townships of Rensselaer and 

 Danbury. 



The Drift in Ottawa county has not been so carefully observed as in 

 adjoining counties, yet it is believed not to be an exception to the 

 general view which has been taken of the Drift deposits in the Fourth 

 District. The banks of the Portage consist, wherever seen, of unmodi- 

 fied Drift. The upper six to eight feet are of a light brown color, and 

 the first two or three very rarely contain stones or gravel. It is, perhaps, 

 to some extent made up of a re-deposit of the finest parts of the hard- 

 pan, incident to the sifting agency of the waves and currents of Lake 

 Erie when it stood at a higher level ; but it is generally too gravelly to 

 admit of that origin, and its finest parts, if deposited in that way, can 

 not be separated or distinguished from those parts of the unmodified 

 Drift which are also very fine, and which graduate insensibly into it. In 

 general, also, such re-deposits by the action of Lake Erie consist of sand 

 with no stratification, while this fine clay is seen sometimes, as at Toledo, 

 to be handsomely arranged in horizontal and oblique laminations, with 

 alternations of very fine sandy layers. 



