walcott.] ALABAMA. 147 



This series of qnartzites in their several varieties makes up the main body of the 

 Bine Mountains range in Alabama. 



These strata are the probable equivalents in Alabama of the Ocoee conglomerates 

 and slates of Prof. Safford, of the Tennessee survey, by him referred to the Silurian 

 age underlying the Potsdam. By Prof. Sterry Hunt the entire system of crystalline 

 schists has been referred to pie-Silurian and pre-Cambrian age. My own observations 

 in the field while inclining me to the latter view, have not been sufficiently extended to 

 enable me to form an independent judgment on this point. * * * Mr. F. H. 

 Bradley refers to the Lower Silurian all the metamorphic rocks of North Carolina as 

 far east as Franklin. 1 



This inetainorphic belt is apparently the same as the altered Silurian 

 rocks of Prof. Bradley, as stated by Prof. Smith, and also of the altered 

 rocks forming the northward extension of the Blue Ridge through Ten- 

 nessee, Virginia, and Maryland into Pennsylvania, where it forms the 

 South Mountain. 



In the report for 1875 Prof. Smith states that he has followed the 

 Tennessee subdivisions as found in Prof. Safford's published volume. 2 

 Under the caption of " Lower Silurian," the Primordial or Cambrian 

 period is divided into (1) Acadian epoch and (2) Potsdam epoch. The 

 Acadian slates and conglomerates of Talladega County are considered 

 to be the exact equivalents of Safibrd's Ocoee slates and conglomer- 

 ates. 3 The direct superposition of the sandstone referred to the Pots- 

 dam, upon the Acadian slates, is not well shown in Alabama. The 

 formation consists of line-grained conglomerate, heavy-bedded sand- 

 stone, and sandy shale. The most characteristic markings of the rocks 

 of this formation are the sandy rods, caused by the filling in with sand 

 of the burrows of a mariDe worm, tScolithis linearis.* 



The Knox sandstone and Knox shales are referred to the Canadian 

 period, thus following Prof. Safford's arrangement in Tennessee. The 

 Knox sandstone is considered to rest upon the sandstone referred to 

 the Potsdam, but uo contact of the two formations in such a position is 

 known to him. The sandstone is a calcareous sandstone associated with 

 hard calcareous shales. 



The Knox shales are very similar to those of Tennessee, aud succeed 

 conformably the Knox sandstone. The line between the Knox shale 

 and the Knox dolomite is difficult to draw since the lower part of the 

 dolomite contains beds of blue limestone similar to those in the upper 

 part of the shale. This report contains much detailed information of 

 the strata referred to the Cambrian in Alabama, and will be principally 

 used in the description of the Cambrian rocks of that State. 



In a paper on the iron ores of Alabama, with special reference to 

 their geological relations, Prof. Smith states that the Potsdam sand- 

 stone frequently contains large amounts of iron, principally as limonite. 

 In the Kahatchee hills, in Talladega County, the sandstone is some- 

 times impregnated with iron in the form of specular ore or as magnetite, 



'Op. cit., pp. 21, 22. 



2 Report of progress of the geological survey of Alabama for 1875. Montgomery, 1876, pp. 7, 8. 



« Op. cit. , p. 127. « Op. cit., p. 14. 



