27 
sometimes of considerable size and riel mess they cannot be depended on to extend 
so far in depth or length as true veins. The walls of gash veins are not striated. 
Segregation or Bedded Veins are cracks following the bedding of the rock, but 
like gash veins their walls are not striated, and they cannot be depended upon to 
continue in depth. 
Stock Rocks are networks of small veins in a rock carrying ore, portions of 
which are rich enough to work but with no true lode formation. 
Artesian Areas. 
An Artesian Area, is an area over which artesian water may be obtained by 
sinking, whilst artesian water , is water which, when either tapped by a bore or 
shaft, rises and flows above the surface in the form of a spring, the supply being 
fairly constant. Everyone is, of course, familiar with the stereotyped encyclopedia 
definition: “ Artesian wells derive their name from Artois, in France, where they 
Were first largely used in Europe, although they were employed in the East from 
very early times;” and “An artesian area is a basin-shaped depression surrounded 
hy high hills.” The last of these is not only incorrect, but misleading, as any 
one ignorant of the subject would naturally think that an artesian water supply 
depended entirely upon the surface configuration of the area. 
The subject of artesian areas is a very complicated one, and without a 
thorough geological knowledge, with a certain smattering of dynamics, it is impos¬ 
sible for anyone to give a reliable opinion on the subject, as the main points to be 
considered are—1st, the shape of the country; 2nd, the geological formation; 3rd, 
a cause why, if a bore were put down and water struck, that it should rise above 
the surface. 
The conditions of an artesian area are as follows:— 
1. The surface must be comparatively low, and there must be much higher 
land on some side or sides of it. 
2 . The geological formation must consist of one or more pervious beds, such 
as sand, sandstone, limestone, &c., between two impervious ones, such 
as clay, sliale, &c. 
3 . The pervious bed must outcrop on the high land and dipping under the 
plain between the clay beds, whilst the point selected for the well must 
be considerably below this porous outcrop, which collects and stores the 
rain. 
4 . The supply will depend upon the rainfall and the surface catchment area 
of the outcrop of the pervious beds, whilst the pressure will depend upon 
the level at which the water stands in these beds above the surface where 
the bore is sunk. Springs are generally met with at the edges of 
artesian areas inland, but along the coast the water-bearing beds discharge 
themselves very often below the sea level. 
As a rule, the main point, what an artesian well is, is lost sight of, its princi¬ 
pal characteristic being that the water rises above the surface, and is therefore a 
ho wing well, not being, as many suppose, simply a very deep tube well, from 
’which the water has to be pumped. The definition should therefore be a flowing 
w ^'l, and the description of the area where space is limited should be left out, 
without it is said to be an area in which artesian water may be obtained. An 
Wesian well being a flowing well, there must be some cause for this phenomenon; 
he basin-shaped area will not account for this, as there is no reason why this 
Water should not break out as springs, filling the whole valley to the level at which 
10 water is standing in the water-bearing beds. 
An artesian area is mainly dependent on the geological formation of the 
( °uiitry, which must consist of one or more pervious beds, overlaid by impervious 
} eds, dipping under the plain, the pervious beds outcropping on the highest 
