GENESEE SLATE. 
219 
The mass decomposes much less rapidly than the soft calcareous shales below it, and the 
thin slaty laminse resist atmospheric action for a long time. On the Genesee it presents two 
regular courses of concrelions or septaria, with numerous single ones scattered through it 
without order. These are often divided by seams of crystalline matter; but many of them 
are without these seams, the inside being entirely composed of crystalline carbonate of lime 
of a deep resinous color, from its strong impregnation with bitumen, which often flows from 
the small cavities when the mass is broken. 
In lithological character this rock is entirely uniform throughout the district, presenting 
itself upon the margin of Cayuga lake and upon Lake Erie, having the same deep black color 
and laminated slaty structure. Neither is there any change in its organic remains ; the same 
forms, and many of them almost equally abundant, are found throughout its entire extent. 
The greater portion of this rock is destitute of fossil remains, and it is only toward the upper 
part that they occur. 
The position of this formation on the map is at the junction of the purple and brown colors ; 
it being too thin a mass, and occupying too little surface, to be represented by itself. In the 
Fourth District this rock borders the margins of Cayuga and Seneca lakes, and is visible in 
all the deep ravines, forming high cliff’s above the Tully limestone, which latter always pro¬ 
jects boldly, forming a cliff, or a cascade on all the small streams. It crosses Seneca county 
in a curve, its extreme northern limit being some distance north of the village of Ovid, while 
its final disappearance to the south on the lake shore is ten or twelve miles distant. This 
circumstance is owing to the great height of the central part of the county above the lake, the 
highest part of which is between 400 and 500 feet above the level of the water of Seneca, and 
more than 500 above Cayuga lake. On the western side of Seneca county, this rock extends 
as far south as the town of Starkey in Yates county; and from thence it sweeps around in a 
northwest direction through the towns of Benton, Seneca and Gorham, and stretches south¬ 
ward along Canandaigua lake, to within a few miles of its southern extremity. From this 
place westward its outline is extremely irregular; and in the western part of Ontario county, 
it forms some small outliers in the towns of Bristol and Richmond. From the outlet of Co- 
nesus lake in Livingston county, its direction is southwesterly, till it comes to the level of the 
Genesee valley in Groveland and Mount-Morris. From the western side of this valley, its 
course is northwesterly to the south part of the town of York, whence it continues westward 
to Allen’s creek. Beyond this point it extends northwesterly into Bethany, and thence by an 
irregular west and southwest direction to Lake Erie. 
The outline and direction of this rock is interesting, as showing the southern limit and 
extent of the Hamilton group. The irregularities in outline, and the great southern depres- 
rotk will in fu'ure be considered only ns a member of the Portage group, its local name will be the more appropriate. The 
aboriginal name of this place was Squakie Huh; and the gorge at its outlet received the name of Squakie Hondah, which 
signifies a gorge with a river opening into a plain, which is beautifully applicable to this spot, where the river, after pursuing 
a meandering course for twenty miles through a deep gorge, and over three successive cascades descending more than five 
hundred feet, flows out into the beautiful broad and fertile valley of the Genesee. These aboriginal names have been fur¬ 
nished me by E. N. Horsford, Esq. 
28* 
