FREQUENCY OF OCCURRENCE OF FERROMANGANESE IN CORES 
FIGURE 2 
When nodule frequency at the surface is com- 
pared with nodule frequency at depth in the 
sediment column, it is clear that most nodules 
Occur at the sediment-water interface. For ex- 
ample, there are four times as many nodules at 
the surface as in the next 3 feet of underlying 
sediment in the North Pacific. 
Lu 
1S) 
4 
LL 
[4 
=) 
wn 
SUBSURFACE 
2 18 24 
DEPTH IN CORE (FEET 
Source: Horn, D. R., B. M. Horn, and M. N. Delach. Distribution of Ferromanganese 
Deposits in the World Ocean. In Ferromanganese Deposits on the Ocean Floor, Horn, D. R., 
ed., IDOE, National Science Foundation, Washington, D.C., 1972, p. 15. 
