existence, and in many instances is practically bottomless so far as
human exploration is concerned.

There are, however, reefs or lodes which are not persistent in depth.
Sometimes the lode formation is found only in the upper and newer
strata, and cuts out when, say, the basic rocks (such as granite, etc.)
are reached. Again, there is a form of lode known among miners as a
"gash" vein. It is sometimes met with in the older crystalline slates,
particularly when the lode runs conformably with the cleavage of the
rock.

Much ignorance is displayed on the subject of lode formation and the
deposition of metals therein, even by mining men of long experience.
Many still insist that lodes, particularly those containing gold, are of
igneous origin, and point to the black and brown ferro-manganic outcrops
in confirmation. It must be admitted that often the upper portions of
a lode present a strong appearance of fire agency, but exactly the same
appearance can be caused by oxidation of iron and manganese in water.

It may now be accepted as a proven fact that no true lode has been
formed, or its metals deposited except by aqueous action. That is to
say, the bulk of the lode and all its metalliferous contents were once
held in solution in subterranean waters, which were ejected by geysers
or simply filtered into fissures formed either by the shrinkage of the
earth's crust in process of cooling or by volcanic force.

It is not contended that the effect of the internal fires had no
influence on the formation of metalliferous veins, indeed, it is certain
that they had, but the action was what is termed hydrothermal (hot
water); and such action we may see in progress to-day in New Zealand,