Oji the Polished Limestone of Rochester. 241 



tremity, the rock continues at nearly the same level ; is may be 

 that the direction is oblique to the line of the canal. In another 

 place, however, we are able to trace the edge of the polish, and 

 can see no reason why the polished surface should not continue, 

 unless it is a slight depression of the surface. The Erie canal is 

 cut through this polished rock for many rods, near the Bethel 

 church. These are the chief localities on the west side of the 

 Genesee, till we ascend a mile and a half southwards to the rapids. 

 In excavating the Genesee valley canal, many rods of the pol- 

 ished surface have been exposed and blasted through. It is the 

 same, but a darker limestone, and some of the polish is exquisitely 

 fine. It extends westwards, under soil ten to fifty feet deep. 

 The polished surface extends along the river by the rapids, from 

 ten to fifteen feet above the bed of the river, and descends from 

 the south towards the north, as the rocks in the rapids. The 

 polished surface descends slightly a few feet or a rod or more, and 

 then pohshes a descent of six to twelve inches ,• passes on slightly 

 descending, till it forms another polished descent like the former. 

 Sometimes a surface is polished which gradually rises on all sides 

 to a few inches above the general level of the surface. On the 

 east side of the Genesee, the polished rock may be seen just be- 

 low the falls, and at the level of the rock over which the waters 

 fall ninety six feet into the abyss, where Sam Patch lost his life 

 in leaping from the top of the falls. At eighty rods south and 

 up the Genesee, the same occurs perhaps fifteen feet above the 

 river, and twenty above the last mentioned. At sixty rods still 

 farther south, and at the depth originally of more than twenty 

 feet, it forms the bottom of the sewer in Main street for several 

 rods ; and at sixty rods east on the same street, has been struck 

 in sinking for a well. At half a mile south of this, and nearly 

 the same east of the Genesee, the Erie canal was excavated 

 through this polished surface for perhaps sixty rods. The rock 

 here is two feet thick, and is the rough, ragged, geodiferous lime- 

 stone of Eaton, as it has been commonly called, though it is by 

 some doubted, as it lies at a lower level, whether it is the same 

 rock which passes by this name at Lockport. A fine polish was 

 often given to this rough surface. To speak of no more places, 

 this rock, already polished, is found at various depths, and in 

 large surfaces, over a tract three and a half miles in length from 

 east to west, and one mile and a half in breadth from north to 



Vol. XXXVII, No. 2.— July-October, 1839. 31 



