HUDSON RIVER BEDS NEAR ALBANY 491 



In the final report of the first district (1843) Lieut. Mather (4) 

 changed the name Hudson river slate group to Hudson river 

 group. Of its fossil contents he reports (p. 369) : " These rocks 

 contain few fossils except fucoids, and these are extremely abun- 

 dant in some of the strata. A few specimens of testacea only have 

 been found in this group, although it is well exposed to view 

 over a great extent of country in the first geological district." 

 The strata of the Hudson river group in the northern counties 

 (including Albany county) are described under two heads (p. 375) : 



1 Those east of the anticlinal axis, which are upturned. 



2 Those west of the anticlinal axis which are but little dis- 

 turbed. 



The anticlinal axis above referred to ranges from near Xew 

 Baltimore by Saratoga lake to Bakers falls. 



Of the upturned strata it is said that they all dip 

 eastsoutheast, and in regard to the less disturbed beds 

 Dr Mather remarks (p. 377); '^ The horizontal and slightly 

 inclined strata of slates and grits of the Hudson river 

 group, lying on the west of the anticlinal axis, as traced from New 

 Jersey to Saratoga lake, were formerly considered as more recent 

 strata than the upturned rocks of the Hudson valley, and as resting 

 wfioonformably on them. It was not until the labors of the geo- 

 logic survey were more than half completed;, that suflQcient evi- 

 dence was obtained to establish the fact with certainty that they 

 are of the same geologic age.'^ It is farther stated that the strata 

 could be traced across the line of disturbance only in the Mohawk 

 yalley, that however, the Trenton and the Utica formations were 

 recognised in the tilted strata by their fossils, the Utica shale by 

 the graptolitee. 



It follows from these quotations that Dr Mather distinctly cor- 

 related the Hudson river beds with the Lorraine beds, or rather 

 with the Frankfort slates of the Mohawk valley, that he farther 

 believed that the Trenton and Utica beds could be recognized 

 in the Hudson valley. As to the latter, it is evident from his 

 description of the Utica slate that he did not yet discern between 

 the Normans kill graptolites and the Utica shale graptolites and 

 considered all graptolite-bearing shales as being of Utica age; 



