carbonaceous mud derived from a coal seam, or the materials 
forming one, were filtered through the fissure 
the narrow seam below. 
eS is ee 7] zara Bs we 
aT OWE eae ama Rg * ik aes 
RSS S Come 6 i Belges  BE oes 
Pet os seat ee en ~ \ ‘< is d 
aes ee m a 
a, a, a, Limestone of Devonian age. 
6, Coarse sandstone in curved lamine. 
c. % Ash colored and greenish ash colored underclay. 
7 
a, , 
b, 
d, d, Coal seam with shaly mud containing fish teeth. 
ock, 
and it couke sie have resulted from a participation in the causes 
then operating to produce those extensive beds of sand, clay, 
shale, and coal, which make up the coal measures. 
It should not be forgotten that this point is near the northeast- 
rh margin of the coal measures, anh beyond the limits of any 
Own productive coal seam; a few isolated patches of sand- 
stone and shale being all the remaining evidences of the exten- 
Sion of this series in that vicinity. Mies i 
“he fissures and caves occupied by the lead ores in Wisconsin, 
Ullinois, Towa and Missouri are apparently of similar character 
and origin; the period of their production, being a point of 
discussion, Whatever may be said to the contrary, 1t appears 
still very certain that these lead-bearing fissures have no connex- 
won with the rock below; and also that the character of the 
fissures, with the materials filling them, indicates an action 
above. That these cavities were excavated, and subsequently 
ited or partially filled with the ores of lead, zinc and iron, by 
Infiltration from above, seems, as elsewhere stated by the writer,* 
a8 well settled a problem, as that the coal seam just noticed is due 
to infiltration from above. The age of the rock in which the lead 
* The same yi i igin of the lead — 
ews, in reference to the origin of the a 
and have been published by Mr. J. D. Whituey. 
