University of North Dakota. 15 



16 — Potsdam Sandstone. Potsdam Period. 



Hinckley, Minn. 

 17 — Magnesiaii Limestone. Canadian Period. 



Near Madison, Wis. 

 18 — Landeilo Flags. Lower Silurian. 



Moffat, Scotland. 

 10 — Cak'iferous Sandrock. Canadian Period. 



Little Falls, X. Y. 

 20 — Chazy Limestone. Trenton Period. 



Chazy, N. Y. 

 •21 — Trenton Period. Xashville Group. 



Nashville, Tenn. 



22 — Trenton Limestone. Trenton Period. 



Trenton Falls, N. Y. 



23 — Cincinnati Group. Trenton Period. 



Cincinnati, Ohio. 



24 — L'tica Slate. Trenton Period, 



ITtica, N. Y. 



25 — Hudson River Shale. Trenton Period. 



Cohoes, N. Y. 



20 — Oneida Conglomerate. Medina Period 

 27 — Medina Sandstone. Medina Period 



Oneida Co., N. Y. 



^ledina, N. Y. 



28 — :\rc"<lina Sandstone, with Lingula cuneata. Medina 

 Period. 



Medina. X. Y. 



21) — Clinton Iron Ore. Xiagara Period. 



Rochester, X. Y. 



30 — Pentamerns Limestone. Xiao^ara Period. 



Rochester, X. Y. 



31 — L^pper Green Shale, M'ith Graptolites. Xiagara Period. 



Rochester, X. Y. 



