Geology of Alabama

S KETC H OF T H E ‘ Geo o of A ab gy ama. B EUGENE ALLE N m y 51 m , Eh . D ,, State Geolo is g t . The five great divis ions ,based u pon the peculiarities of the f c organic life o each,into whi h ,according to Professor Gekiei, r s fi the geological ecord has been clas i ed are " (1 ) the Archaean , sometimes cal led the Azoic (lifeless) . or E ozoic (dawn of life) (2 ) the Pal eozoic (ancient life) or Primary (3) the Mesozoic (middle life) or S econdary ; (4) the Cenozoic (recent life) or _ Tertiary,and (5) the Post - Ter tiary or Quaternary The following table shows the order of successi on of th e m o of m stratified for ati ns Alaba a,together with the position in the geological column of those formations either Wantin g or not yet recognized as occurring in the ,S tate 2 a t c y F L G o o O A ABAM A . T ABLE O F GE O LO GIC A L - FO A T IO RM NS . R c - e ent S o ils an d alluvia m. li- i l oxi or coas t formatio ns . ‘ Pleis tocene . River terraces (s ec ond bottoms ) . ‘ Ozark sands . 5 L afayette s ands an d pebble beds . m o s . Mioc ene . Pascagpn l a an d Grand Gulf for ati n 'g Xigfiggg white li mes tone . Claiborne . Buhrs tone . H atch eti b ee . ’ l Bas hi or oo d s b u fi . T us c ah oma. Nanafalia. Naheola. ‘ S u c ar noc h ee. Clayton or Ru tl Ripley Ro l m tten i es tone . Cretac eous l T uskal oos a. Wa nting in A l abama. Wa t i n n ing A l abama. Pe an Wa t A l rmi n ing in abama. oal M a es C e s ur . 1S u b - Carboniferous D evo a B ac k h ni n l s ale . -t n Clm o or Red mountain , ' E r en ton o r P l e a es o e . _ lh m im t n k ox d olo e an d en n mit er l;~ oc c o ' o r M Ch ol c c o ontevall os hales ,inc ludi ng th e a i a We1 s e t C mbr n n r quar zi te . oosa s l e C ha s . ' A r c haean Crystalline s c his ts i n n the t givi g de ails concerning these formation s, it will be, for many reasons, mos t convenien t to consider them in t his orical order . G L Y L 3 E O OG OF A ABA MA . C RYS T L LINE s c ms r s A . ARC H /E AN. These rocks occupy a somewhat triangular s haped area in th e eastern part of the S tate,bounded by a l ine ru nnin g ap proximately as follows " F rom the Georgia line,near the north ' eas tern corner of Cleburne county, southwes tward through Cl ay and Coosa into Chilton, an d th ence eastward throu gh E lmore,Tallapoosa,Macon and L ee to th e Georgia l ine again , i about opposite Columbus . Th ese rocks difler from th e other rocks of the State in being made up of distinct, often well crystalli zed minerals, of which quartz, feldspars ,micas , an d horn blende form the great mass of the rocks in qu es tion ,whil e subordinated to these, other mineral s occ ur; either forming rock varieties of limited distribu tion, or as ores of valuable m m m w s etals,as inerals of econo ic value,or other i e of interest . ' As before stated,the great mass of these crys tal l in e rocks are aggregates of the minerals,quartz,feldspar and mica,often ' f associated with hornblende . O these the quartz an d h orn rid m m m m bl e e alone so eti es for great rock asses . Granite, gneiss, mica schist,quartzite and hornblende s chist,or slate, are th e most abundant of these rocks, while soapstones, or m s n m m m e steatites,and li e to es,are of uch ore li it d occurrence. " They are all disposed in beds of varying thickness,which are seldom in horizontal position, bu t are usu ally tilted at some considerable angle to the horizon,th e dip or slope of these beds bein g prevalently to the southeast,while the trend or strike of their upturned edges is,as a rule,to the northeast and south n m t h west . In crossi g this country fro the nor hwest to t e southeast,it can n ot fail to strike the obs erver that,as he ap pr oach es the s ou theastern border, he has evidences of con n f a A s tan tl y increas ing amou t o dec y among the rocks . long th is southeastern border they are often nothing more than stratified clays,which are the res u lt of their decay from th e ' ac tion of the atmos ph eric for ces . This decay often reaches to a depth of fifteen or twenty feet from the surface,as may be ’ d s n s een in many of th e railroa cut . I these clays,ledg es or thin sheets of quartz,which is practical ly unaff ected by th e “ weather,may be seen protrudin g ; or broken down by alterna 4 GEOL OG Y OF A L AB AM A . tion s of heat and cold, they cover the ground with angular fragments,that in process of time are worn into th e rounded pebbles that are so widely distributed over the rest of the S tate . The conclusion seems unavoidable,that the southeast ern part of these crystall ine rocks is older,or has been longer subjected to sub - aerial decay, than the parts further to the n orthwest . T h e Crystalline S chists,or Archaean ROCks ,have, in other parts of the U nited S tates,been arranged in two series,called ‘ H u r om an and L au r en tian ,the latter being the older of the two and presumably th e oldest rocks of which we have any knowl m edge . By so e geologists these are considered as older than an y of the stratified fossiliferous rocks,W hile by others they, as well as the H u ronian , are thought to be the altered and c rystallized sedimen ts o f the Cambrian ,S ilurian,and perhaps l ater ages . W t m d m ithou atte pting to deci e any of these atters for . A labama,we may again recu r to the fact that th e rocks n ear ' “ th e eastern border of this region appear to be mu ch ol der ,or at least to have been very much l onger exposed to the dis in te ‘ grating action of the atmosphere than those towards the west, o r northwest,and it is almost certain that some of the rocks “ along this northwestern border are nothing more than th e C hoccolocco or Montevallo shal es and the Weisner quartzite m m to e eta orphosed,or changed crystallin schists . ‘ l n o i — r an i Mater ia s of E co m c " al u e. The g tes and g n ei s s es m m h above na ed are used in so e slig t degree as building stones, an d deserve more attention than they have received from quar m rymen . The sa e rocks, especially the granites , which are found chiefly along a belt running northeast from near Brad ford,in Coosa county,are also largely used for the manufacture o f millstones . r an d D ol omi —N M a bl es tes . ear Talladega and Sylacauga o ccurs a bed of good crystalline marble that ' has been worked at mb ,and e m m a nu er of localities has yi lded so e fine aterial . In L ee county, near Opelika, there is a crystalline dolomite which is white,and would make a fine ornamental and build n f m ing sto e,hardly to be distinguished ro marble . This sub stance has for years supplied the Chewacla lime works and m gives a li e of very superior quality . G Y A B 5 EOLOG OF LA A MA . — oa ~ S ps ton e or S teatite. This rock is found in several parallel n m belts runni g northeastward fro the Coosa river. It has been e in C m o quarri d ha bers . county for the manufacture f mon “ u ments ,headstones,and the like,and for furnis hing fir e- proof lining to the Chewacla lime kilns,for which purpose it answers . m ad irably . “ P or cel ai n Cl ay - The decomposition of the feldspar of granites, an d other rocks,gives rise to the formation of clays which,when not mixed with other substances,are suitable for m the anufacture of porcelain and fine ware . The best kn own occurrences of this clay are near L ouina,Randolph coun ty, and S a in C N near oc patoy, oosa,and otasulga,in Macon .

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