EXPLANATION OF ADDITIONAL PLATES. 



A Section of Ball's Cave, in Schoharie county. From Mr. Mather. (See page 227 of this volume.) 



Plans and Sections of the Shawangunk Lead Mine, near Wurtzboro', in Sullivan county. From the 

 drawings furnished by Mr. Cotheal, of New- York. (See pages 50 and 414.) 



View of the Coal Hill or Rossie Lead Mine, in Rossie, St. Lawrence county, as it appeared in the sum- 

 mer of 1836. (See pages 48 and 413.) 



Map of the Lead Vein in Rossie, St. Lawrence county. (See the pages just referred to.) 



Ground Flan of the Beds and Veins of Magnetic Iron Ore, or Magnetic Oxide of Iron, at Adirondack, 

 Essex county. (See page 16.) 



Map of Mining District of Monroe, Orange county. Reduced from the copy furnished by Peter Towi»- 

 SEND, Esq. (See page 5.) 



View of the Strata of Potsdam Sandstone, (composed chiefly of quartz,) as exhibited at the " Walled 

 Banks," about four miles from the village of Keescville, Essex county. 



Hopper-form cavities and crystals of Marly Clay, at Bull's duarry, Madison county, and at Camillus, 

 Onondaga county. (See page 119.) 



