GEOLOGY OF THE HONEOYE-WAYLAND QUADRANGLES 9 



The entire section of this formation is exposed along Honeoye 

 creek from the Monroe milldam in Honeoye Falls to the north side 

 of the bend half a mile south of North Bloomfield, except for a small 

 hiatus in the middle of the formation between the two villages. 

 The lower beds may be seen along the bed of Spring creek and the 

 upper tiers in the quarry of the Genesee Lime Company twO' miles 

 southwest of Honeoye Falls. The basal layer, specially rich in 

 corals, outcrops over an area of half an acre near an old limekiln 

 three miles west of Honeoye Falls near a north and south road 

 one and one-eighth miles west of Spring creek. Some of the lower 

 tiers outcrop in the road south of Five Corners, and there are 

 several field outcrops farther south in the region drained by Stony 

 brook. 



The fauna of the Onondaga limestone is very large ; a list of 

 species found in this formation, given in State Museum Bulletin 

 63, contains 3 fishes, 39 crustaceans, 13 cephalopods, 3 pteropods. 

 38 gastropods, 15 lamellibranchs, 48 brachiopods, 4 crinoids and 30 

 corals ; total 193. 



MARCELLUS BLACK SHALE 



The blue Onondaga limestone is succeeded by black, carbonaceous 

 shales and soft, dark impure Hmestones to the thickness of 41 feet 

 in the Livonia salt shaft but somewhat thinner on the line of out- 

 crop. On these quadrangles this shale is terminated at the top by 

 the Stafford limestone, and it constitutes the lower division of the 

 " Marcellus shale," as described by Hall and Vanuxem. 



The lower beds are mostly calcareous and fossiliferous, while the 

 upper are composed mainly of densely black bituminous and pyri- 

 tiferous shale in which occur spherical concretions six inches to one 

 foot, six inches in diameter. 



This formation is rich in hydrocarbons and is the source of the 

 natural gas produced by the shallower gas wells of this region. 

 Many of the concretions are septaria and the cavities within them 

 occasionally contain a small quantity of petroleum. On account 

 of the compact character of this rock, gas wells terminating in it 

 are not very productive except when a crevice or large pocket is 

 penetrated. Fossils are abundant, specially in the lower more cal- 

 careous part on this formation. 



The following species were found in the Marcellus shale and 

 limestone in the Livonia salt shaft, in the upper black shale and 

 concretions : 



