148 D.WHITE — RELATIVE AGES OF KANAWHA-ALLEGHENY SERIES 



r coal, Upper Freeport. 

 ;/ fireclay: 

 |=Ff=p{f=^ 3' limestone, Upper Freeport. 

 8' shale, with ore. 



miirfi::, 



- J -'- ■ ■ - 1 ■ • •■.:■■ ■: 



mmm. 



• ' • ::■ ■ X-^:-- 



W::SP : : 



>n 



m&z 





\F_: 



Vf-'.v.-.'.M.'.'.v. 



:fe-(^ 



p 



o 



O 

 O 



3 - 

 ■>< 



^ ■■,', ;, '1: . -, 



t=c^c 



'■.'•••V--.-T.- ■■•• : ••••- • 



: . J .-'-:( ■ '■ ■ ^>te V 



26' sandstone. 



1' shale. 



6' coal, Lower Freeport. 

 2' fireclay. 



:;' limestone. Low er Freeport. 



7.")' sandstone and shale. 



Id' shale. 



2' coal, Upper Kittanning. 

 :;' fireclay or shale. 

 2' limestone, Johnstown ce- 

 ment bed. 



40' shaly measures. 



2' coal. Middle Kittanning 

 2' fireclay. 



:$(>' shale and sandstone. 



4' coal, Lower Kittanning. 



•_'.">' sandstone and shale, with 

 ore. 



1' ore, Buhrstone. 



8' limestone, Ferriferous. 



7' shale. 



2' coal, Clarion, upper split. 



25' slaty shale. 



3' coal, Clarion, lower split. 

 2' fireclay. 



27' shale and sandstone. 



•>' coal, Brookville. 

 :;' fireclay. 

 Massive >and-tone (Pottsville). 



Figure 1. — Generalized Section of the Allegheny 

 Series in Clarion County, Pennsylvania. 



following pages reference will fre- 

 quently be made to the very useful 

 and excellent work last mentioned. 

 The general composition of the 

 Allegheny series in northwestern 

 Pennsylvania is indicated in the 

 following section, figure 1, prepared 

 by Mr Chance to show the sequence 

 in Clarion county* It differs from 

 the sections in Jefferson, south- 

 ern Armstrong, or Butler counties 

 chiefly by the development of the 

 Scrubgrass coal and the concom- 

 itant expansion of the interval be- 

 tween the Brookville bed and the 

 " ferriferous limestone. "f 



CLARION GROUP 



Plant beds of the group. — Trie in- 

 terval embracing the lower portion 

 of the Allegheny series, from the 

 top of the Homewood sandstone 

 (Pottsville formation) up to the top 

 of the "Ferriferous limestone,'' is 

 known % as the Clarion group. The 

 ordinary thickness of this group 

 is about 70 or 75 feet in the Alle- 

 gheny valley. Two coals — some- 

 times three or more, two of which 

 are locally workable — are usually 

 present in this section. 



In the Clarion group of western 

 Pennsylvania determinable fossil 

 plants are generally very rare, most 

 of the scarce material from this 



* Report of Progress, Second Geol. Survey 

 Penn., VV, p. 32, Fig. 2. Reproduced by Doctor 

 I. C. White : Bull. U. S. Geol. Survey, no. 65, p. 

 105, fig. 55. 



f Other typical sections for these counties are 

 quoted in Bull. U. S. Geol. Survey, no. 65. pp. 

 104-111 ; and summary final report, Second Geol. 

 Survey Penna., vol. iii, part 2, pp. 449, 450, etc. 



J Report of Progress, Second Geol. Survey 

 Pa., VV., p. 41, 49. 



