26 



NOTES OJs' THE GEOLOGY 



thickness, averaging about six inches, of moderately good quahty, and occasionally 

 calcareous. The upper is nodular, but seldom of sufficient thickness to prove of 

 value. Both seams sometimes disappear altogether. The seam of ore in ISTo. 32 is 

 near the bottom of the stratum — an irregular band of nodules, of low grade. Many 

 years ago it was extensively taken out to supply the old furnace on Decker's creek, 

 where, in combination with other and better ores, it was successfully worked. Iso. 

 24 contains an irregular band about a foot thick which has never been tested. 



The Conglomerate, No. 21, is a curious stratum varying in thickness from a few 

 inches to several feet. It is made up of fragments of limestone, sandstone, and iron 

 ore, in size from fine sand to that of a man's head. These fragments are usually 

 rounded, as if by currents existing before or during the time of deposition. Thin 

 layers of homogeneous sandstone or shale may be traced to a considerable distance ; 

 and at one point there is a layer of iron ore one foot thick. The extent of this 

 stratum is not known, and I doubt whether it exists west of the river. 



The Sandstone, ISo. 20, appears to be equivalent to the one described at Pitts- 

 burgh in the Pennsylvania Report. The lower portion is usually compact, affording 

 a handsome and durable building stone. The lines of deposition are often well 

 marked, and not unfrequently the iron there deposited gives the rock a yellowish tint. 

 The upper portion ])resents a curiously shattered appearance where exposed, due 

 evidently to the decomposition of nodules of impure iron ore. 



Shales, Fossiliferous, IvTos. 26 and 27, form an interesting little group with the 

 following section : Shale, calcareous, blue, gray or black, 3 ft. ; dark shale, with many 

 small ferruginous nodules 12 ft. ; calcareous nodules 1 ft. ; olive shale 4 ft. ; brown shale 

 6 ft. Excepting the brown shale at the bottom, which does not appear to be per- 

 sistent, all the layers are richly fossiliferous. The following species have been 

 obtained from this series : Hemvpronites crassus, Clionetes Smitliii, C. granulifera, Pro- 

 diictus Nehrascensis, P. Prattenanus, P. semi-reticulatus, Orthis carhonaria, Atliyris 

 suhtilita, Sj)irifer planoconvexus, S. cameratus, .Lima retifera, Amcidopecten carhona- 

 rius, A. occidentalis, Nucida pania, N. ventricosa, I^. (f) anodontoides, Nuculana 

 hellistviata, Yoldia carhonaria, Y. Stevensoni, Edmondia Aspenwalensis, Astartella 

 concentrica, Macrodon oTjsoletus, Solenomya radiata, Macrocheilus primigenius, M. 

 ventricosus, PJuomj^Jialus rugosus, Belleroi^lion Montfortianus, B. percarinatus, B. car- 

 honarins, B. Stevensanus, B. Meehianus, Pleurotomaria Gh^ayvilliensis, OrtJioceras 

 crihrosum, Wautilus occidentalis Petalodus Alleglianiensis, and undetermined species of 

 Myalina, Pleuropliorus, Pdmondia, Deltodus, Lopliodus and Ctenoptyclmis. Fish teeth 

 are very rare ; a few crinoidal stems and bryozoans have been found near the top. This 

 series is well exposedat several points on Decker's creek, but thefossils arenot usually in 



