6 Geological Histori/ of the Ozark Uplift — Broadhead. 
minerals and showed that such rebuilding was a prevalent 
process, constituting an important element in those changes 
heretofore desig lated metamorphic, thereby contributing an 
important factor in the elucidation of that mysterious process. 
Perhaps the most important single determination by pro- 
fessor Irving, and one of his latest, was the demonstration of 
the origin of the iron ores of the lake Superior region. By a 
series of admirable investigations he traced step by step the 
transformation of the ores from original earthy carbonates of 
iron to their present forms, nnd made it altogether clear that 
they were primarily deposited as sediments in a manner closely 
similar to that of the iron onjs of the Coal Measures. This 
discovery has given added significance to the association of 
these ores with carbonaceous shales, and has led to the recog- 
nition of the iron-bearing series as marking in some sense a 
pre-Cambrian carboniferous period. 
The characteristics of professor Irving as a scientific investi- 
gator and writer are too well known to the readers of this 
magazine to need analysis here. Personally, to those who 
came Avithin the circle of his intimate acquaintance, he possessed 
rare charms of character. Sincere, frank, conscientious in the 
highest degree, he was a warm and true friend. Possessed of 
a rollicking brusque humor, his intercourse was marked by a 
freshness that was a source of constant enjoyment and attrac- 
tion to his intimate associates. No phrase better expresses it 
than picturesqueness. Modest and retiring, the number of his 
close friends was not large but their attachment to him was 
strong. The full strength of these attachments has only been 
realized in their breaking. 
He leaves a wife, a daughter and two sons. The artistic 
skill of Mrs. Irving appears in some of the sketches and par- 
ticularly in many of the microscopic illustrations of her hus- 
band's works. 
THE GEOLOGICAL HISTORY OF THE OZARK UPLIFT.* 
By G. C. Broadhead. 
To the southern part of Missouri, the general term ''Ozark 
Mountains" has for a long time been applied. This district 
*Abstract read before American Association for the Advancement of 
Science ; Cleveland meeting, Au2;ust. 1888. 
