CURRENT PRE-CAMBRIAN LITERATURE 539 
The history, varieties, and characters of corundum, and its mode 
of occurrence in the holocrystalline rocks, are fully described. 
Smith’ gives a general account of the character, distribution, and 
structure of the crystalline rocks of Alabama. The rocks are altered 
sedimentary and igneous rocks. The altered sedimentary rocks, called 
the Talledega or Ocoee series, is referred to the Algonkian, and the 
altered igneous rocks are referred to the Archean. 
The Talledega series is found in the northeastern part of the state, 
in four or five roughly parallel belts, running northeast and southwest, 
the strata in general dipping to the southeast. The series comprises, 
in order of abundance, clay-slates or argillites, in places impregnated 
with graphite, quartzites and quartzite conglomerates, and crystalline 
limestones or dolomites. The slates, quartzites, and conglomerates 
resemble very strongly certain strata of undoubted Cambrian age, and 
it is probable that some of the strata included with the Talledega are 
altered Cambrian rocks. As yet, however, no fossils have been dis- 
covered in them. 
The altered igneous rocks occur in three main belts roughly paral- 
lel with the sedimentary belts in the northeastern part of the state. In 
order of abundance they are gneisses and mica-schists, cut by dikes 
of granite, diorite, and various hornblendic, pyroxenic, and chrysolitic 
rocks. 
Gold ores are associated with both the sedimentary and igneous 
series. Their mode of occurrence is briefly sketched. 
Brooks,” in petrographical notes on some metamorphic rocks from 
Alabama, makes general statements concerning the geology of the 
metamorphic rocks of Alabama and Georgia. The metamorphic 
rocks of Alabama and Georgia may be differentiated into two series. 
The older, or crystalline series, includes crystalline schists and gneisses, 
whose origin is doubtful, together with large masses of gneissoid 
granite. The younger, or clastic series, is typically made up of phyl- 
lites, sericite-schists, chlorite-schists, conglomerates, quartzites, crystal- 
*A general account of the character, distribution, and structure of the crystal- 
line rocks of Alabama, and of the mode of occurrence of the gold ores, by E. A. 
SmitH: Bull. Geol. Surv. of Alabama, No. 5, 1896, pp. 108-130. 
2Preliminary petrographic notes on some metamorphic rocks from Eastern 
Alabama, by A. H. Brooks: Bull. Geol. Surv. of Alabama, No. 5, 1896, pp. 177-197, 
