TOURTELOTTE PARK. 179 
zation, yet the process of silicification, which usually attends ore deposition, 
has gone on more extensively than in places where more ore has been found. 
This process results in the formation of zones of jasperoid, which follow 
fractured zones and faults, and by means of this jasperoid the faults may 
be traced continuously over the surface. Microscopic study of this rock 
shows that some iron was deposited at the same time with the silica, but 
apparently no great amount of the rarer metals. 
TOURTELOTTE PARK MINING MAP. 
The detailed map of Tourtelotte Park on the 300-foot scale comprises 
essentially the whole of the productive area, and in it are situated nearly 
all the mines which have been described. The region displayed is the 
same as that on the 800-foot map, but is slightly more detailed and comes 
out clearer by reason of the enlargement. On this map the blue Leadville 
dolomite and the blue limestone which overlies it are distinguished by 
different. colors, and the Contact fault which separates it is represented as 
such, while on the 800-foot map both these formations are grouped together, 
and the Contact fault was omitted. There are also put in several small 
faults, which were not important enough to be shown on the 800-foot 
scale, but which are sufficiently well marked to be put into the more 
detailed map. Such a fault, for example, is that found in the Camp Bird 
mine, which is represented as a splinter of the Silver Bell fault running 
across to the Justice fault. The faults of the east-west system which have 
not been described in the 800-foot map of Tourtelotte Park have mostly 
been described in connection with the mine workings. There are seven 
"cross sections and one longitudinal section, which show the geology as 
developed in the mines and on outcrops as accurately as possible. Nearly 
all the points shown have already been discussed, and a study of the map 
and sections will explain the structure far better than any written descrip- 
tion could do. The ore bodies are not shown in the sections, but the 
oceurrence of the ore in general throughout this whole area may be 
summarized as along the Silver and the Contact faults, or in the blue 
limestone which lies between these two. 
The accompanying plates give some idea of the general appearance 
of Tourtelotte Park. Pl. XXIII is a view taken from the west side of 
Spar Gulch, just north of the Best Friend shaft, and looks south up Spar 
