112 NEW YORK STATE MUSEUM 



The bedding- and upper contact lines are irregular. Thick- 

 ness 14-15 feet. 



5 Compact, finely crystalline and homogeneous dolomitic rock, 

 showing traces of fossils and slickensides. Beds showing Stro- 

 matopora common. In places the rock has a porous appear- 

 ance and is rich in geoditic cavities, which are lined with dolomite 

 and calcite crystals. Thickness 19 feet. 



This stratum forms the lower portion of the cliff at the first cut 

 on the gorge road, and the basal part of the mass left standing on 

 the river side. Heads of Strom atopora may be seen in this 

 rock, some of the geoditic cavities having replaced this fossil. This 

 is about the summit of the beds exposed in the quarry at the end of 

 the railroad section. 



6 Earthy, compact dolomite in thin layers, which give the cliff 

 the appearance of a stone wall. Toward the top the rock becomes 

 more compact and heavy bedded, this giving the appearance of an 

 overlying stratum. This rock is full of geodes lined with pearl spar 

 or dolomite, the cavities ranging in size up to that of a fist or larger. 

 The beds are generally less than a foot in thickness, the average 

 being from 3 to 6 inches. Toward the top of the cut, the rock 

 becomes more compact and finely crystalline, but otherwise remains 

 similar. Pearl spar geodes remain common to the top. The thick- 

 ness of this mass, at the beginning of the gorge road, is about 45 

 feet. 



The total thickness of the limestone exposed on the gorge road is 

 in the neighborhood of no feet. This is double the thickness found 

 at the quarry, the distance between the two points in a straight line 

 being about three miles or nearly four following the curvature of the 

 river. The rate of increase in thickness, or the amount of dip of the 

 strata is therefore about 20 feet to the mile. 



Almost the only recognizable fossils found in these limestones, 

 excepting the crinoid fragments, are the hydro-coralline St r o m a - 

 topora (concentrica Hall) and the coral Favosites. 

 Both occur in the middle and upper portions of the exposed mass, 

 and may generally be seen in the weathered upper surfaces of the 

 limestone beds. Thus wherever these beds are exposed on the sur- 



