HAWORTH. | Ore Deposits. 119 
the latter’s views also. In speaking of the process of secondary 
enrichment he says: ‘‘The process is one phase of the gen- 
eral work of superficial alteration, but represents a particular 
portion of the general process which is locally of considerable 
importance. It causes the enrichment of the ore body at and 
below water level by the migration into and deposition within 
it of certain amounts of the ore bodies from the belt of weath- 
ering. In the Joplin area it differs in certain particulars 
from the process of reaction between the sulphides outlined 
by Weed and Emmons. In all these instances the reducing 
action is believed to be mainly the influence of one sulphide 
on the other, and the relative affinity of the metals for oxygen 
and for sulphur is very important. In the Joplin region the 
affinity for oxygen of the three metals, iron, zinc, and lead, is 
important, as usual, and they have gone into solution in the 
order named. In the presence, however, of an excess of or- 
ganic reducing agencies all the sulphides seem to have been 
reduced with equal facility and without order.’’ 
It is difficult to understand in what essential respect this 
sulphide enrichment as above outlined differs from the general 
views of ore formation expressed by Winslow. 
But Van Hise lays special stress on certain structural con- 
ditions which are worthy of note. After having reviewed 
the Wisconsin area, wherein he held that the ore bodies in 
Wisconsin were deposited first by ascending water and en- 
riched subsequently by descending water, he likens the entire 
area of southeastern Kansas and Missouri to the Wisconsin 
district. In this respect it will be seen that he embodies the 
views of Jenney regarding ascending waters, believing that 
ore deposition originated in this way, and later the views of 
Winslow, although not so expressec, regarding the influence 
of descending waters. but there is an essential difference in 
this, that Van Hise would have all the ore brought from below 
and later concentrated by surface action, while Winslow would 
have all the ore obtained originally from the overlying forma- 
tions. It is probable, it seems to the writer, that both these 
views may be correct, and that Van Hise should have credit 
_ for originating the true explanation for such ore bodies by 
combining the two processes. However, there are certain 
