Hawor tH. | Geology of Lead and Zinc Ores. 57 
and of Wiesloch in Baden, as well as other deposits in that 
duchy and in Wurtemburg. 3 
“Deposits in Jurassic Rocks.— Here, likewise, there is a 
dearth of such ores in America, though lodes of Peru and 
Chili have been assigned to this formation. In Europe they 
are comparatively common. The more noteworthy of such 
are those of Santander in Spain (though the rocks may be 
Cretaceous), and those of Les Malines, Clairac and other lo- 
calities in France. 
‘* Deposits in Cretaceous Rocks.—The existence of these ores 
in Cretaceous rocks is somewhat doubtful; at least, at the 
more important localities. The deposits of Algiers are as- 
signed to this formation; those of Laurium in Greece have 
also been placed there by some geologists, though the gener- 
ally accepted opinion is that they are in the Silurian. Some, 
at least; of the ore bodies of Santander in Spain appear to 
be in Cretaceous rocks. In Peru, silver lodes traverse these 
rocks. In Mexico the Sierra Mojada ores have been placed 
at this horizon. 
‘* Deposits in Tertiary Rocks.—The only noteworthy deposits 
of lead or zinc in Tertiary rocks are those of Tunis in Af- 
rica, which are placed in the Eocene.”’ 
Kansas-Missouri Area. 
The lead ores and zinc ores of the Galena-Joplin area are 
found in limestones and included flints of the Mississippian 
series, with comparatively unimportant amounts in little 
patches of shales found here and there throughout the dis- 
trict. Beneath the Mississipian series lie rocks of greater 
age, which may have a great importance in connection with 
the question of deep mining. This great complex of forma- 
tions belonging to different ages rise to the east onto the 
Ozark dome, and have their gently upturned edges beveled 
by erosion, so that one traveling eastward is constantly ap- 
proaching rocks of greater geological age. Some geologists 
believe that these underlying rocks may have an important 
influence, in one way or another, on the Kansas ore bodies, 
or in connection with their development. A brief discussion 
of their properties and sequences, therefore, is desirable. 
Farther east in the Archzan area the oldest stratified rocks, 
