Ashburner.] 05Z [Peb. 16, 



Along the Aughwick creek near Potts's Gup in the lower strata there is 

 a fine exhibition of ripple marks. 



These rocks make ridges and in the Aughwick Valley are not of eco- 

 nomical importance ; in New York the Hamilton contains a number of 

 very fine flagstone quarries. 



Marcellus ( Cadent Lower) black slate. 



Upper member (Nos. 62, 61 and 60) 571 feet. ) 



Middle " (No. 59) 20 " V 875' 



Lower " (Nos. 58, 57 and 56) 284 " ) 



This formation might be mofe properly divided into an upper and lower 

 portion as the lithological characters of each are quite distinct ; what we 

 have called the middle member may prove to be but locally deposited. 



The tipper member consists of brown, gray, olive and black argillaceous 

 shale with occasional seams of flaggy and slightly calcareous sandstone in 

 the upper part, and seams of non-calcart-ous sandstone iu the lower part. 

 The sandstone and shale, but more par;icularly the latter, are very much 

 stained with iron and bituminous matter. 



The middle member is made up of shaly argillaceous limestones, alter- 

 na'ing with greenish-gray lime shale. The exact position of this member 

 of the series may be a little above or below that given in the section. The 

 only place where it seemed possible to study this portion was in the valley 

 of Blacklog Creek, near Orbisonia, where the dip of the strata was rather 

 uncertain, and too far from the section line to make its position certain. 

 Although it has been thought best to suggest only a local deposit of this 

 limestone, economically considered, yet it seems quite certain that the 

 horizDn may not be more calcareous in one locali y than in another, but, on 

 account of the associated strata being very argillaceous, the carbonate of 

 lime may be more generally disseminated in one place than in another ; in 

 the former case producing nothing but a calcareo-argillaceous shale, and in 

 the latter case an argillaceous limestone. 



The lotrer member consists of black fissile slate and black and brown 

 shale, the surfaces of both being very much stained with iron and coated 

 with bituminous matter. In this lower member in the valley of the 

 Juniata, above and below Lewistown, occur irregular deposits or beds 

 of coal, the vestiges of a vegetation which appears to have been air breath- 

 ing or terrestrial. The lower horizon of the series is marked bj' an 

 important ore bed No. 56 which primarily is a proto-carbonate of iron but 

 ■which has been changed at its outcrop by atmospheric action into a brown 

 peroxide of iron. 



It is not an infrequent thing to find the black shale and slate of the lower 

 member very much contorted and dipping in an opposite direction to the 

 general lay of the strata. These transverse dips are seldom of an_v extent 

 and if relied upon lead to errors in constructing a section. It seems proba- 

 ble that some of the faults which have been located In the Marcellus and 



