CANANDAIGUA AND NAPLES QUADRANGLES 29 



the bed of the creek at Cheshire. They enter largely into the 

 composition of the lake wall on the east side from Genundewa 

 south to Woodville, but here the rock exposures are extensively 

 overgrown. In the Bristol valley they are displayed in the large 

 ravine of Wilder creek and from there southward in the Keed 

 and Packard ravines and in several other smaller gullies on both 

 sides of the valley. The south branch of Beebe brook in the 

 northwest corner of Bristol township flows through a small 

 gully cut in the shales of this horizon, and in the town of Rich- 

 mond the rocks are exposed in the cliffs of Mill gull. Here, a 

 short distance above the outcrop of Genundewa limestone, the 

 cliff walls are handsomely banded by alternating layers of black 

 beds recurring among the blue gray layers. 



Standish flags and shales 



Thin, uneven, bluish gray flags and olive shales. This is a 

 thin bed of rocks probably not exceeding 15 feet in thickness, 

 but it has seemed entitled to distinctive designation because it 

 marks a transition from the argillaceous shales of the West 

 River beds into the arenaceous sedimentation, characterizing 

 for the most part, the mass of the Portage strata. The beds 

 were originally designated by the writer " transition shales " in 

 recognition of the fact referred to. It is not a persistent deposit 

 for any great distance from the region immediately under con- 

 sideration. The mass, thinning out toward the west, disappears 

 altogether in the Genesee valley and by its absence the over- 

 lying bed of black shales (Middlesex shales) is brought directly 

 on the West River beds. The beds show some difference from 

 those below in faunal content. Exposures are seen in the locali- 

 ties already mentioned where the outcrops are sufficiently con- 

 tinuous, specially in the Middlesex valley in the ravine 50 rods 

 north of the Lee schoolhouse and in other ravines at the north 

 to Middlesex Center, and on the west side of the valley in the 

 Goodrich gully running up into South hill and ravines to the 

 north; in the Canandaigua lake valley, in the Standish gully and 

 the ravines from Woodville to Cook point, and in the upper 



