24 NEW YORK STATE MUSEUM 



FEET 



3 Hard, dark dolomites with cavities. Strop heodonta 



profunda, crinoid fragments and corals are found. The 

 upper part of this exposure has the stratigraphic position of 

 the lower Shelby dolomite which contains Guelph fossils.. 25 



4 Covered interval 20 



5 Even bedded dolomites 5 



6 Dark dolomites with Stromatopora 10 



7 Fine, hard, thin-bedded dolomite 5 



8 Dark brown dolomite with corals 12 



9 Covered interval. Probably represents upper Guelph hori- 



zon 15 



Total thickness of Lockport series l . . 122 



The above section does not include a few feet at the base and at 

 the top of the section. However, the total thickness of the Lock- 

 port dolomites is not far from 130 feet. 



The fauna of the Lockport dolomite exclusive of the Guelph species 

 is not an abundant one in the Rochester section, the more pro- 

 lific development being to the west in Orleans and Niagara counties. 

 Of about 40 species described by Hall, less than 10 are mentioned as 

 occurring in Monroe county. 



The total number of Guelph species at present known in 

 New York is 71. Species to the number of 52 are recorded from 

 Rochester and of these 17 species are common to the Niagaran fauna 

 of New York. Most of the species from Rochester are found in 

 white chert nodules which occur in the upper part of the dolo- 

 mites. The Nellis quarry was formerly the source of a number of 

 these nodules, but as the quarry is now filled they can no longer be 

 obtained. 



In excavating for the new West High School building, which is but 

 a few rods from the Nellis quarry, a considerable amount of material 

 was taken out which yielded a number of the nodules with finely 

 preserved fossils. From these excavations there were also obtained 

 a number of fine crystallized specimens of dolomite, calcite, fluorite, 

 gypsum and galena. Aside from the fossils in these nodules, 

 Guelph species are quite rare in the dolomites. Occasionally, how- 

 ever, specimens are found lower than the chert-bearing dolomites as 

 known in the vicinity of theliigh school building. 



