388 
VADOSE ORE DEPOSITION 
chite ore-bodies of Copper Basin, near Prescott, Arizona, refer 
to this type of deposit. 
Conglomerate-ores form another great group under this head¬ 
ing. The copper deposits of Kelvin, Arizona, may be mentioned. 
The gold deposits of Altar, in Sonora, Mexico, are well known. 
Pitching synclines, or troughs, are among the most important 
geologic structures with which vadose ore deposits in stratified 
rocks are associated. In its broader geologic features each min¬ 
ing district is likely to be in a distinct basin. The smaller basins 
in which ore-bodies are localized are also often of synclinal 
character. 
In moist climates where the vadose zone is necessarily thin, 
the immediate connection between ore-deposit and trough is 
not always at first discernible. Yet on the west slope of the 
Ozarks the great Joplin zinc belt is in the bottom of a wide 
shallow syncline pitching westward. The main mining camps 
of the zinc district. Galena, Joplin, Webb City and Cartharge, 
are all located in basins caused by low cross-flexures in the 
great trough. The Lake Valley silver deposits are all intimately 
associated with small pitching synclines Among the copper- 
deposits of Bisbee, Arizona, all the larger mines are located in a 
distinctly pitching syncline. According to Van Hise the hema- 
titic ores of the Penokee-Gogebic range south of Lake Superior 
are similarly deposited in pitching troughs formed by the inter¬ 
section of inclined quartzite layers and transverse sheets of 
trap-rock. 
Miners are prone to expect ore deposits to occur in connection 
with faults. For those who are accustomed to ascribe a magmatic 
source to all ore-materials it is difficult to separate the two ideas. 
Many ore deposits having no manifest relationships with the 
depths of the earth are also intimately associated with lines of 
faulting. Faulting of more or less tilted beds initiates imponding 
conditions which frequently are the direct cause of ore-localiza¬ 
tion. A porous layer or band which before may have been the 
channel of freely flowing groundwater is abruptly cut oflf or 
dammed, permitting the ready lodgment and accumulation of 
metallic precipitates. 
An example in which the relationships of the ore-bodies and 
25 Trans. American Inst. Mining Eng., Vol. XE, p. 228, 1909. 
26 American Jour. Sci., (3), Vol. XEI, p. 117, 1891. 
