Chapter X. 



PENNSYLVANIAN. 

 Color, dark gray. 

 Symbol, 12. 

 Distribution: Guatemala, central and eastern United States, New Brunswick, and Nova Scotia. 



Present though not distinguished from Mississippian throughout the Cordillera, the Arctic 



region, and Newfoundland. 

 Content: "Coal Measures" (Pottsville to Monongahela inclusive) of eastern North America 



and their equivalents where distinguished; Carboniferous hmestone of Guatemala. 



Mapped elsewhere with Carboniferous undivided. 



Pennsylvanian areas. 



Page. 



D 15-16 Guatemala and Chiapas 425 



H 14 Central Texas 427 



I 14 Northern Texas 428 



1 16 Alabama 430 



I-J 16, J-K 17-18. .Appalachian coal field 430 



I-K 14^15. .Western Interior coal region 455 



J-K 15-16.. Eastern Interior coal region 466 



K 16 Michigan 468 



K 19 Rhode Island and eastern Massachusetts 469 



L 19-20 New Brunswick 473 



D 15-16. GUATEMALA AND CHIAPAS. 



The Carboniferous of Guatemala and Chiapas was recognized by geologists 

 who preceded Sapper, but has been more accurately determined by him. He has 

 described it in two works-^^*'**'^ From the later one we quote: 



In Alta Verapaz one may distinguish two series or formations — a lower, which consists of 

 quartz, conglomerates, sandstones, clay slates, and graywacke, which has been called the Santa 

 Rosa terrane by DoKus and Mont-Serrat, and an upper series of limestones, dolomites, and 

 conglomerates or breccias, which consists of both these rocks. These limestones and dolomites 

 are both of very dark color and often strongly bituminous. The graphitic limestone occurs near 

 Tucuru. 



In the older rocks of the Santa Rosa terrane are quartz conglomerates and puddingstones. 

 They rest directly upon the Archean. In many places they contain pebbles of crystalline 

 schists as large as nuts. The higher beds consist of sandstones, slate, shales, and graywackes 

 which are sometimes interbedded and also show gradual transitions and even pass through 

 coarse sandstones into conglomerates. The Santa Rosa strata also include limestones which 

 contain crinoids and also Fusulina granum avense. [Sapper mentions local occurrences of 

 gypsum, yellow shales and slates and clay slate, and other rocks.] 



The age of the Santa Rosa terrane is definitely fixed by the discovery of typical Carbon- 

 iferous fossils which were determined by Stolley under the direction of Zittel. They are 

 Syncladia hiserialis Swallow, Lonsdaleiajloriformis Fleming, FenesteUa sp., Nucula cf. ventricosa, 

 Leda sp. n., Natica sp. [lower Peimsylvanian or possibly upper Mssissippian — G. H. Girty]. 



The fossils have been found only in the upper horizons of the Santa Rosa and consequently 

 the age of the lower horizons is not fixed. The thickness of the Santa Rosa in some places 

 rises to as much as 200 or 300 meters but is very different in different locahties. 



The upper terrane of the Carboniferous formations has a thickness of 600 to 800 meters 

 and is shown by abundant fossUs to belong to the upper Carboniferous [Pennsylvanian^-Girty]. 

 The fossils are Fusulinqi, granum avense Roemer, BeUerophon cf. costatus Sow., Afhyris ambigua, 

 Aihyris sublameUosa Hall, Productus semireticulatus Martin. In the vicinity of Senahu the rocks 

 are chiefly dark-gray dolomites which readily decompose into a sand and show no traces of 



425 



