100 The American Geologist. August, 1896 
{idditional work before any definite conclusions can be estab- 
lisiied. However, we may infer from tlie present data, tliat 
at or near the close of tlie Tertiary era there was a radical 
rearrangement of the stream courses of tliis portion of the 
continent. The problem of the Tertiary lines of drainage in 
the upper Mississippi basin is one of great interest and it 
awaits only future researches for its solution. 
NOTE ON THE FORMATION OF GOLD ORE. 
By K. VON Kraatz.* Translated by H. V. Winchell. 
In spite of the many revelations made by gold mining in 
the last fifty years and in spite of the tremendous practical 
interests that are continually leading to new searches for the 
sources of gold, we are still but poorly informed as to the 
origin of this noble metal and the conditions governing its 
deposition. It is true the secondary occurrences in river 
sands and in the so-called placers (Seifengebirge) are ex- 
plained without difficulty, although even here widely different 
theories are expressed on one point, viz., the explanation of 
the occurrence of nuggets and the supposed reenrichment of 
gold sands that have been already worked out. It will be 
readily admitted that large gold nuggets cannot be trans- 
ported l)y the floating or rolling action of water; and most 
geologists have believed until recently that they are found too 
seldom in the solid quartz to account for those found in the 
alluvions. But since more careful observations, like those of 
Howitt in Australia, have been made upon the occurrence of 
nuggets embedded in rockf it is known that pieces are found 
in quartz (more widely scattered to be sure) of equal size with 
those of the secondary deposits; and hence the size of placer 
nuggets no longer compels us to accept the theory of solution 
and reprecipitation of the gold. We have, therefore, to deal 
with transportation of the larger masses and the supposed 
recharging with gold. 
Now it is certainly not an unjustified assumption for us to 
conclude that the gold nuggets did not grow as we now find 
*Zeitschrift filr praktische Geologie, May, 1896. Extract from the 
Verhandlungen des Naturhist, Med. Vereins zu Heidelberg, N. F. V. 
Bd. i Heft. Carl Winter's Universitatsbuchhandlung in Heidelberg. 
"fThe newly discovered gold fields of Coolgardie in southwestern Aus- 
tralia have also yielded a considerable numV)er of nuggets. 
