CORRELATION WITH FOREIGN ROCKS. 207 



Notwithstanding their greater resemblance to the foreign ex- 

 amples distinguished as " pyroxene-granulites" and regarded as 

 ordinary members of the crystalline schists, it is but fair to state that 

 mineralogically the charnockite series often show close affinities to the 

 old pyroxenic eruptives just referred to. In the Cortlandt series, for 

 instance, there are pyroxenites, amphibolites, 

 The Cortlandt Series. hornblende, augite and biotite-norites which 

 resemble in composition those of the complex at 

 Pallavaram. G. H. Williams has also recorded the association of her- 

 cynite and corundum with the Cortlandt series and these minerals we 

 know too are frequently found in connection with the charnockite 

 series. 1 



Williams 3 found similar rocks in the neighbourhood of Bal- 

 timore, Maryland, whilst in Pennsylvania, at a point intermediate 

 between the Cortlandt series of Peekskill on the north-east and 

 Baltimore on the south-west. Prof. J. F. Kemp described, from the 

 supposed Archaean strip that crosses Bucks County, a mass of 

 norite containing hypersthene, green monoclinic pyroxene, brown 

 hornblende, garnet, magnetite and apatite. Near this rock occurs 

 a limestone with an abundance of accessory minerals such as 

 light-green pyroxene, titanite, rutile, orthoclase with microperthitic 

 albite, zircon, apatite, pyrite, scapolite and plagioclase. Kemp 

 points out the similarity existing between the minerals occurring at 

 this point and those of the Cortlandt series at Peekskill to the north- 

 east, and again at Baltimore and North Delaware to the south- 

 west. He also points out that these rocks resemble many of those 

 in the Adirondacks where the basic rocks contain titanic ores. 3 



The description of these rocks by Kemp might very well apply 

 to some exposures of the charnockite series in the Madras Pre- 

 sidency, and yet, as he says, they strongly resemble also the 

 eruptives of the Cortlandt series. Cases of this kind show how 

 closely the pyroxene-granulites approach true eruptives in the 



1 See Williams' papers, Amer. Journ. Sci., 3rd Ssr., Vol. XXXI (1886), pp. 26-41 

 Vol. XXXI (1887), pp. 135-144, 191-199. and 243 j Vol. XXXV (1888), pp. 438-448. 

 iBull. U. S. Geol. Surv., No. 28 (1886). . 

 3 Trans. N. Y. Acad. Sci.> Vol. XII (1S93), p. 71. 



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