THE 
MANGANESE-ORE DEPOSITS OF INDIA 
PART II 
GEOLOGY 
(MODE OF OCCURRENCE AND ORIGIN) 
CHAPTER XI. 
GEOLOGY. 
General — Classification of Indian manganese-ore occurrences according to 
formation — The khondalite series. 
General. 
The rocks composing the earth's crust can be divided into two main 
groups : — (1) the fossihferous ranging in age from 
The Archaean com- j. j_ n ■ j /r>\ xi, r m-j- 
p]g^ recent to Cambrian ; and (2) the imiossiliierous, 
and as far as is known the pre-fossiliferous, or 
pre-Cambrian rocks. The word ' Archaean ' is by many authors taken 
as synonymous with ' pre-Cambrian' ; but it is customary in 
America to restrict the word ' Archaean ' to the older portion of the 
pre-Cambrian rocks, using the term ' Algonkian ' for the unfossiliferous 
rocks intermediate in age between the Archaean and the Cambrian. 
In India Dr. Holland proposes to use the term ' Purana', meaning 
' old ', to designate the series of rocks occupying a position analogous 
to that of the Algonkian of America. 
The Archaean rocks can be supposed to form a continuous shell round 
the earth and to underlie all the younger rocks. These latter rest in 
more or less isolated patches on the Archaean shell, areas of which are now 
II A 2 
