Art. IX. ] Watson, Mauj^aurse Ore Deposits of Georgia. 159 



I. Midille Cambrian shale. Coosa Valley, near Blaine, Chfrokee county, 

 Alabama. H. N. Stokes, analyst. Bulletin Alo. i63, (/. S. Geol. Survey, 1900, 

 p. 283. 



II. Oostanaula (Conasauga) shales, about 2 miles northwest of Carters- 

 \ilie, liartow couniy, Ceirgi.i. J. \\ . McCandless, analyst. " Paleozoic 

 Group,' Cieol. ..'iwvev of Geori;/n, 1S93, p. 285. 



III. Lijrht-colored hyilro-rni:a shale on the ridije above the Etowah river 

 iron briilge, south 01 Carteisville. Oi the border of the metamorphic zone. 

 "Palenzoic Group," Gedl. Swvev of Georgia, 1893, p. 2S4. J. M. .McCandless, 

 analyst. 



I V^ Light-red shale, in the valley i mile southwest of Cartersville. 

 ^'Paleozoic Group," Geol. Sunnv of Geo>\ia, 1893, p. 284. J. M. McCandless, 

 analyst. 



V. Oostanaula ((Tonasaug.i) shales, about 2 miles northwest of Carters- 

 ville. "Paleozoic Group. Geol. Su'vey of Geoi^'ia, 1893, p. 285. J. M. Mc- 

 Candless, analyst. 



77u' Knox Dolomite. — The Knox dolomite lies next above 

 the Conasaui^a shales. The lower beds are probably Cambrian, 

 but, owing to the paucity ot fossils in them and the striking 

 uniformity in litliologic character, the entire formation is here 

 classed as Silurian. Hayes says:' 



' From the few fossils which hive been found, it appears probable that a 

 transition from Cambrian to Silurian occnis in the lower third of the formation, 

 but it is grtnerally impossible t ■> determine this line of division. ..." 



It is a massively-bedded, semi-crystalline, gray-mngnesian 

 limestone, containing abundant nodules and layers of chert, 

 and IS one of the most persistent formations in the Southern 

 Appalachians. 



Weathering of the dolomite, by removal in solution of the 

 soluble calcium and magnesian caibonates, has covered the 

 limestone surface by a prevailingly thick mantle of insoluble si- 

 liceous clays abundantly adnh.xed with chert-fragments and 

 masses. The residual clays derived from the dolomite are 

 often light in color, containing comparatively small amounts of 

 iron oxide. In many places, however, the clays derived from 

 the limestone are deep-red ferruginous clays, containing much 

 iron oxide. The proportion of clay to chert varies considera- 



' "Geologic Atlas of the United States," Rome Folio, U. S. Geol. Survey, 

 .1902, p. 3. 



