
338 STRUCTURAL AND FIELD GEOLOGY 
or other valuable mineral, the prospector—always a sanguine 
man—will feel confident of success. Stopping ever and anon, 
as he proceeds up-stream, to examine the contents of the 
alluvial deposits, he may at last reach a point above which 
no fragments or particles of metal or ore can be found. 
Searching the adjacent valley slopes, the observer discovers 
perhaps scattered fragments of veinstone and possibly ore. 
But whether these do or do not occur, the prospector would 
certainly be justified in digging pits or trenches down to the 
solid rock, in hopes of striking the ore-formation itself. While 
the search for such formations is, for obvious reasons, most 
promising in valleys, yet the Jand-surface separating one 
valley from another—more especially if it be a hilly region— 
must not be neglected. For, owing to long-continued 
weathering, such surfaces are often sprinkled in places with 
angular fragments, or partly mantled by sheets of rock- 
rubbish. Should lodes traverse such a tract, they are almost 
sure to be betrayed, even in the absence of conspicuous 
outcrops, by the presence of loose fragments, or shode-stones, 
as they are termed by Cornish miners. By the careful track- 
ing of these stones their source may be located. It need 
hardly be added that the prospector who has a good working 
knowledge of ores, and is quick to understand leading 
geological structures, is more likely to succeed than the 
geologist who, however expert he may be in unravelling and 
interpreting rock-structure, is yet unfamiliar with the various 
“indications” that reveal so much to a keen-eyed mining 
man. The latter, however, whose experience may have been 
gained in some limited region, is often at a disadvantage 
when he begins prospecting in a new country. Not infre- 
quently he is possessed with the belief that the mining region 
in which he was brought up must be the type of all others. 
If the only valuable lodes of that region have a north and 
south direction, he expects that the same is likely to hold 
good elsewhere—no matter what the geological structure of 
the ground may be. He often makes similiar assumptions as 
to the gossans. The auriferous reefs of the country he has 
left may crop out as ridges of ferruginous cellular quartz, and 
when similar gossans are encountered in a totally different 
area, he is apt to jump to the conclusion that these also must 

