336 THE JOURNAL OF GEOLOGY. 



this report, as they must with all who have to do with the Paleozoic 

 formations of the states adjacent to Tennessee, for the descriptions 

 and classifications of Dr. Safford are remarkably true to nature. 

 Chapters III to VI inclusive are devoted to a general description of 

 the lithological and other characters of the different formations 

 which make up the area under consideration in Georgia. The Ocoee 

 group, which Dr. Safford places at the base of the Cambrian in Ten- 

 nessee, or beneath the oldest of the fossiliferous strata, is mentioned 

 by Dr. Spencer, but he does not enter into its detailed description. 

 This group of semi-crystalline slates, often designated as hydro-mica 

 schists, talcoid schists, and formerly as talcose schists, and which bears 

 the greater part of the auriferous quartz veins in Georgia and Alabama, 

 is extremely difficult to assign to its proper place in the series, in Ala- 

 bama at least, for we find in the southeastern part of the Alabama Paleo- 

 zoic terrane, some of the Knox or Montevallo shales slightly altered 

 into partially crystalline slates, which we have not yet been able to 

 discriminate from the unquestioned Ocoee. It has therefore seemed 

 to us at least possible that the Alabama representatives of the Ocoee of 

 Tennessee may be, in part at least, altered Cambrian shales. In chap- 

 ter VIII the river alluviums and other formations later than the Car- 

 boniferous are mentioned, and it is interesting to find that remnants 

 of the Lafayette, in the form of pebbles and red loam, are to be found 

 in many places in the Coosa Basin at elevations of loo to 150 feet 

 above the present level of the waters in those regions. These same 

 beds have been traced by the Alabama survey up the Coosa valley to 

 the Georgia line, and they are also to be found extending from the 

 west, for a good many miles within the Alabama line along the Ten- 

 nessee river. 



In chapter IX, dealing with the general physical features of the 

 region. Dr. Spencer directs attention to the ancient character of the 

 streams, and concludes that they long ago reached their base level of 

 erosion, and have since been engaged in widening their valleys. In 

 comparatively modern times (Lafayette), there has been a depression 

 which has allowed the deposition of pebbles and loams at altitudes 80 

 to 150 feet above the present stream level, and of course a still more 

 recent movement of elevation which has brought the streams to their 

 present position. Probably the most striking memorial of these move- 

 ments is to be found in the " flatwoods" of the Coosa Valley. This 

 chapter is illustrated by a number of sections. Chapters X to XX 



I 



