20 Faults. 
Fig. 8a is a horizontal section representing that 
class of ore deposits known as Fahlbands. At Kongsberg, 
Norway, and vicinity, this class of deposits is worked 
for the silver ores contained in the Fahlbands; these are 
parallel belts of micaceous rocks of considerable width 
7/5 + 4 —— | _ 
SS ALBANS 
OANA aIRAADAA 
MOAT ATS FARRAM 
ADA” 
Pd 
FIG 8a. 
Fahlband. Deposit. 
and length. The narrow east and west fissure veins 
a a,b b, are highly productive when they intersect the 
Fahlbands and non-productive when they pass into the 
igneour or crystalline rocks on either side. No deposit 
of this class, to my knowledge, occurs in America. 
FAULTS. 
Fig. 9 exhibits a Normal Fault. The portion of the 
vein D D has moved downward along the fault plane A 
B, from C to D. The vertical dislocation is equal to the 
distance a b, and is called the throw of the fault. The 
VY Ve” 
FIG. 9.—Normal Fault. 
