Fig. 8. — Generalized vertical section of the strata in tlie Tarannon district. 



f 

 C = Weniock Series. 



Cb = FTNYDDOG GRITS : 



1500 feet. 



Ca = NANT-TSGOLLOJf 



Shales : 



450 to 500 feet, 



B = Tarannon Series. 



Bd=DoLGAu Group : 



400 to 450 feet. 



Bc=Talerddig Group : 

 900 to 1150 feet. 





B1)=Gexli Group : 



800 to 900 feet. 



Ba = BRTNMATR GROUP : 



900 to 1000 feet. 



A = Llandovery Series. 



Ac=Twtmtn Group : 



] 50 feet. 

 Ab=Dox&ADPAN Group : 



150 feet ? 

 Aa=FAcnDRE Group : 



100 feet ? 



^Massive micaceous and felspathic grits, 

 flags, shales/and mudstones. 



• Elue and brown mudstones, flags, and sandy shales, with 

 r Monograptus riccartonensis , M. vomeriv.us, Cyrtograptus' 

 i Murchisoni, etc. 



Black bard with M. (C.) spiralis, M. nodifer, 

 ("Pale-green compact mudstones. [B. Geinitzianus, etc. 



Mixed purple and green mudstones, with a few flags. 



I Green shales and flags, with black bands yielding 

 1 Monograptus crenulatus, Betiolites Geinitzianus, etc. 



r 6th Shale-band : shales and small flag?. 



} 5th Grit -band: thick quartzose grits, alternating with 

 I* shales and greywacke'-flags. "Monograptus griestonensis, 

 ' M. subconicus, M. discus, M. nudus, etc. 

 --5th Shale band. ... „ . , 



4th Grit-band. 



-4th Shale-band. 

 -3rd Shale- band. 

 -2nd Shale-band. 

 -1st Grit-band. 



3rd Grit-band. 

 -2nd Grit-band. 



1st Shale-band: flags and thin shales, with Monograptus 

 griestonensis , M. discus, M. Marri, etc. 



I Shales, finely laminated, and numerous thin greywacke- 

 Y flags, with Monograptus crispus, M. ejiguus, M. discus 

 Petalograptus tenuis, etc. 



— Two thick grits. 



I Shales and compact mudstones, with a ew flaggy layers: 

 Y Monograptus crispus, M. exiguus, M. priodon, M. discus, 



etc. 

 J 



) 



Compact bine mudstones, with sandy partings, with 

 Monograptus turriculatus, M. densus, M. exiguus, etc. 



Pale-grey, thinly-bedded mudstones, with occasional flags, 

 i and numerous black shale-bands : Bastrites Linnm, 

 Monograptus Becki, M. runcinatus, M. turriculatus 

 M. proteus, Eetiolites obesus, etc. 



_ ^Black band, with Bastrites maximus, etc. \cretvs etc. 



/Soft grey and black shales, with M. Sedgicickii, 31. dis- 

 vGrey mudstones, with black band: Bastrites peregrinus, 

 / Monograptus crenularis, M. limatulus, e^c. 

 f Finely -banded grey and black shales, with M. conrolutus, 

 \ M. gregarius, M .' leptotheca, C. Hughesi, D. magnus, etc. 

 ^ IJonograptus-fmlriatus band : C. rectangularis, etc. 

 ^Micaceous sardy shales, calcareous mudstones, flags, etc. 

 JDimorpJiograptus Sivanstoni, 31. tenuis, CI. medius, etc. 



