334 Nezv York State Museum 



become more shaly in the upper portion. The sands and 

 conglomerates constituting this deposit came from 

 Appalachia to the east. 



The Lock port dolomite (Hall '39) was named from 

 its occurrence at Lockport, Niagara county, and it is 

 known as far east as Steele's creek in Herkimer. The 

 name is applied to the whole series or group of magnesian 

 limestones or dolomites (including Gasport limestone, 

 Guelph dolomite) deposited upon the Rochester shales 

 and thinning eastward. For a time these limestones were 

 also known as the Niagara limestones, just as the Roches- 

 ter shales were known as the Niagara shales. The Lock- 

 port dolomite has a maximum thickness of about 140 or 

 150 feet in the Niagara area, and is dark gray to choco- 

 late colored. There it carries the Guelph fauna at the 

 top. At Shelby in Orleans county the section shows 

 three feet of dolomite carrying the Guelph fauna ap- 

 pearing after 62 feet of Lockport; then occur 32 feet of 

 Lockport followed again by eight to ten feet of dolomite 

 with the Guelph fauna. The dolomite carrying the first 

 Guelph fauna is known as the Lower Shelby dolomite 

 and represents the first invasion of the Guelph fauna 

 from the west ; the second dolomite bed with this fauna 

 has been called the Upper Shelby dolomite (Clarke and 

 Ruedemann '03). Similar conditions exist at Rochester. 

 The horizon of the Lower Shelby dolomite has been lo- 

 cated in the Lockport section. About ten feet above the 

 base of the Lockport is 20 feet of light gray to white, 

 coalrse-grained, semi-crystalline, pure limestone .Which 

 contains an abundance of crinoid plates and stems and 

 other fossils which give it a distinctive appearance in 

 contrast to the sparingly fossiliferous beds above and be- 

 low. This bed has been termed in the literature of the 



