NOTES ON THE GEOLOGY OF GEORGIA 171 



UNALTERED CAMBRIAN 



The Unaltered Cambrian rocks occupy the northwestern part 

 of the state and are divided into the Lower, the Middle, and the 

 Upper divisions, the first named being subdivided into the Weisner 

 quartzite, Shady limestone, Cartersville formation, Apison shale, 

 and Rome formation (Fig. 3). 



The Weisner quartzite, which is the southern extension of a part 

 of the Chilhowee sandstone of Tennessee, forms a prominent series 

 of ridges and hills along the eastern margin of the Appalachian 

 Valley as far south as Cartersville and a few miles beyond. At this 

 point it is cut out by the Cartersville fault, but farther to the south- 

 west it again appears in a small area near Esom Hill, where it 

 forms the northern extension of a large area just across the state line 

 in Alabama. The lithological character of the Weisner quartzite 

 as described by Hayes is fine-grained and vitreous, though the 

 formation also contains some beds of fine congloi^erate and consider- 

 able siliceous shale. A few imperfectly preserved fossil remains, 

 including brachiopods, corals, and worm tubes, all supposed to be 

 Lower Cambrian, have been found in the formation in the vicinity 

 of Cartersville and Emerson. ' 



The Shady limestone lies immediately above the Weisner quartz- 

 ite, and it has a like distribution. The formation consists chiefly 

 of gray magnesian limestone usually massive but in places shaly 

 and siliceous. It is of very great economic importance, as asso- 

 ciated with its weathered product, occur more or less extensive 

 deposits of barytes, iron ore, and manganese ore. Fossils are 

 almost entirely absent, though in the vicinity of Cartersville a 

 fossil sponge, a lower Cambrian form, his been found. 



The Cartersville formation, as recently defined by Shearer, is 

 known only in the Cartersville district. It is supposed to occupy 

 the same position in the stratigraphic column as the Watauga 

 shale of Tennessee and the Apison shales of Tennessee and Georgia. 

 The formation has a hmited distribution, being confined to one 

 main belt less than twenty miles long. It consists mainly of highly 

 aluminous shales, which are remarkable for their high potash 

 contents, often as much as 10 per cent K2O. Associated with the 

 shales, which are chiefly of a gray or purplish color, there are often 



