HAworTH. | Ore Deposits. LN 
placements, caused as above explained, would have a tend- 
ency to assume curved lines. But if ore deposits are placed 
where they are on account of general earth movements, with 
fissures and faults reaching down hundreds of feet into the 
Silurian and crystallines below, such curved outlines are very 
difficult to explain. 
Theories of Ore Formation. 
The general geologic conditions of the country and the modes 
of ore occurrence in Galena, it would seem to the writer, leave 
no room for doubting that the lead and zinc ores and asso- 
ciated minerals were produced from water solution. There 
is a total absence of eruptive rocks of any and all kinds and 
of the minerals usually accompanying eruptive rocks; and 
likewise a total absence of the generally recognized fumarole 
minerals, or those produced by gaseous exhalations, such 
as certain micas, feldspars, wolframite, fluorite, etc. Still 
further, it is important to note that there is a total absence 
of any and all minerals usually supposed to originate from 
hot water solution, various silicate minerals, such as feld- 
spars and other pegmatite material so common in many 
veins or dykes in crystalline rocks. In the main, therefore, 
the writer agrees with Winslow,” Van Hise, and Bain,™ as to 
the origin and mode of occurrence of the ores. Doctor Jen- 
ney” and Professor Blake” also have studied the ores of the 
southwest district, and have given us their views regarding 
the origin of the same. In addition to these there is inter- 
esting and valuable literature by early writers, probably the 
most notable of which is from the pen of Dr. Adolph Schmidt, 
who spent a number of years in America and studied the ore 
deposits of the Joplin district in the early days of its develop- 
ment and later returned to Kurope, since which time his name 
has rarely been connected with original papers published in 
America. 
There is a unison of agreement by all of the above-named 
33. Winslow, Arthur: Mo. Geol. Surv., vol. VII, p. 467, et seq. 
34. Van Hise, Prof. C. R., and Bain, Dr. H. F.: 22d An. Rep. Director U. S. Geol. Surv. pt. 
2d, p. 31, et seq. 
35. Jenney, Dr. W. P.: ““ Lead and Zine Deposits of the Mississippi Valley,”’ Trans. Am. Inst. 
Min. Eng., vol. 22, p, 171. 
36. Blake, Prof. W. P. 
