Ashlmrner.] biJ\) [Feb. 16, 



it is in the upper part, ami besides ferruginous matter contains micaceous 

 specks. 



In tlie loio'r part, the general ch.iractcr of the strata is very much the 

 same, although apparently containing less iron and mica than the central 

 part. 



In dosccnding from the top to the bottom of the epoch the sandstone 

 which in the upper part soems t') predominate, diminishes, while the shale 

 increases, and the alternations of the two are greater, although of course the 

 sandstone strata must be thinner. The upper part contains the greatest 

 number of remains of fossil life. 



The general charadcr of the Portaje seems the same throughout. The 

 upper part is composed of rather massive brown and gray sandstone alter- 

 nating with beds of olive and gray shale from 10 to 30 feet thick. Toward 

 the centre' the sandstone becomes more flaggy and occurs in thinner strata, 

 while the shale becomes more argillaceous, forms thicker beds and is more 

 varied in color. As we approach the lower horizon the sandstones become 

 thinly laminated and occur in beds but a few inches thick ; the shale is 

 extremely argillaceous and weathers readily into clay. The shale, through- 

 out the whole epoch, contains more or less iron, wliich on exposure readily 

 washes out and is oxydized on the surface, coloring the shale in various 

 shades of yellow, brown and red. 



In New York, Prof Hall reports (1843) that "the upper part of the 

 Chemung is characterized by a general tendency to conglomerate, or gravel. 

 In a few localities the mass becomes a well characterized pudding-stone. 

 This conglomerate (continues Mr. Hall) nowhere attaining sufficient thick- 

 ness or importance to merit a distinct description." 



It is worthy of notice that this conglomerate, which forms several notable 

 "rock cities" in South-western New York and which, probably, is the 

 northern extension of one of the sands of the oil group of Western Penn- 

 s^ivania, seems to be without even a representative at Broad Top. Al- 

 though the sandstones toward the top of the Chemung are massive and 

 coarse grained, yet there seems to be no tendency to conglomerate or 

 gravel. 



Again, cross lamination, or oblique, or current bedding, ripple marks, 

 concretions and limes!(me strata which are so abundant in the Chemung 

 and Portage Epochs in New York, are wanting in Central Pennsyl- 

 vania. The ripple marks in a measure are an exception to this assertion, 

 although they are comparativelj' rare, and though sometimes met with, 

 they would not be dilRcnlt to overlook, especially after studying the fine 

 exposures in the transition layers between No. VIII and No. IX along the 

 E. B. T. II. R., those in the lower Catskill in Smith's Valley, and again in 

 the bottom of the Hamilton on the Aughwick near Potts's Gap. 



The absence of the limestone or limy shale and concretions may be 

 attributed to tlje limited remains of marine life. These in New York are 

 found in great colonies. Not only do we not find any limestone or limy 

 shale, but the whole period is particularly devoid of any calcareous matter 



