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ECONOMIC GEOLOGY 
some are saddle-shaped in cross-section. When alternate 
beds of slate and quartzite are bent into parallel anticlines 
and synclines, lens-shaped spaces are apt to occur along the 
top and bottom of the folds. The spaces taper out on the 
sides, as the beds are there forced together by the lateral 
pressure which caused the folding. Percolating water will 
deposit material in the spaces and thus form lodes which are 
thickest at the crown or cap of the arch, and thin out on 
sach side (Fig. 5). These formations are saddle-lodes and 
are best known in Bendigo, Victoria. . The crown in those at 
the surface had been destroyed by denudation leaving two 
sheets of quartz dipping in opposite directions. As these 
sheets thinned out at a slight depth it was feared that the 
F16. 6.—A FALSE SappLz, 
A false saddle-lode due to spurs 
along the bedding planes from 
a main vein. The line AC 
of the assumed “centre 
country ” would lead away 
from the ore veins. 
mines would be shallow, as search for isolated patches of 
quartz would be too costly. The regular distribution of 
‘hese bodies on the arches of the anticlines was proved 
during the survey of the field by the Geological Survey of 
Victoria, and as similar arches of quartz were found one below 
another along the anticlinal axes, mining was carried to the 
depth of 4,500 feet. Bendigo, instead of being merely a 
superficial field, included for a time the deepest gold mines in 
the world. Lodes are also found on the floors of synclines ; 
but these “inverted saddles” are less rich in gold than the 
anticlines, though they have been profitable, as at Wedder- 
burn. 
As saddle-lodes occur one below another it is important 
fo distinguish between true saddle formations and ** falgse- 
A